diff --git a/README.md b/README.md
index 811b7be..88174a7 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ yarn add schedule-later
 ## Import
 
 ```typescript
-import Scheduler from 'schedule-later'
+import { Scheduler, TimeInMS } from 'schedule-later'
 ```
 
 ## Key Concepts
@@ -122,11 +122,11 @@ In the `StopCancelFunction`, if the `stopRunning` parameter is `true`, it stops
    In this example, the goodMorning function will be called at 7:00 AM. If you want to cancel the morning greeting (for example, the user chose to sleep in), you can call the stopTimeout function.
     
 
-3. Using startInterval with a specific interval, basically a regular setInterval
+3. Using startInterval with a specific interval, basically a regular setInterval. Uses the TimeInMS enum to clearly specify the interval.
 
    ```typescript
    const sayHello = () => console.log('Hello, world!')
-   let stopInterval = Scheduler.startInterval(sayHello, 1000)
+   let stopInterval = Scheduler.startInterval(sayHello, TimeInMS.SECOND * 5)
 
    // Later, if you want to stop the interval
    stopInterval()
diff --git a/package.json b/package.json
index f69b748..91eea5e 100644
--- a/package.json
+++ b/package.json
@@ -1,12 +1,14 @@
 {
   "name": "schedule-later",
-  "version": "1.0.1",
+  "version": "1.0.5",
+  "types": "dist/Scheduler.d.ts",
   "main": "dist/Scheduler.js",
   "author": "Nightness",
   "scripts": {
     "build": "tsc",
+    "pretest": "tsc",
     "test": "./node_modules/.bin/jest --verbose",
-    "watch": "./node_modules/.bin/jest --watch"
+    "prepublish": "tsc && npm run test"
   },
   "devDependencies": {
     "@types/jest": "^29.5.3",
diff --git a/src/Scheduler.test.ts b/src/Scheduler.test.ts
index 1599c62..3169529 100644
--- a/src/Scheduler.test.ts
+++ b/src/Scheduler.test.ts
@@ -1,4 +1,4 @@
-import Scheduler from './Scheduler'
+import { Scheduler } from './Scheduler'
 
 describe('Scheduler', () => {
   beforeEach(() => {
diff --git a/src/Scheduler.ts b/src/Scheduler.ts
index e56caaf..2359f30 100644
--- a/src/Scheduler.ts
+++ b/src/Scheduler.ts
@@ -1,17 +1,32 @@
+export enum TimeInMS {
+  SECOND = 1000,
+  MINUTE = 60000,
+  HALF_HOUR = 1800000,
+  HOUR = 3600000,
+  HALF_DAY = 43200000,
+  DAY = 86400000,
+  WEEK = 604800000,
+  FOUR_SCORE = 1209600000, // 14 days
+  MONTH = 2592000000,
+}
+
 export interface TimeOfDay {
   hour: number
   minute?: number
   seconds?: number
 }
+
 export type TimeUntil = {
   timeOfDay?: TimeOfDay
   date?: Date
   ms?: number
 }
-type StopCancelFunction = (stopRunning: boolean) => void
-type StopFunction = (stopTime?: TimeUntil) => StopCancelFunction | null
 
-export default class Scheduler {
+export type StopCancelFunction = (stopRunning: boolean) => void
+
+export type StopFunction = (stopTime?: TimeUntil) => StopCancelFunction | null
+
+export class Scheduler {
   private static timeUntil(start: TimeUntil) {
     if (start.ms) {
       return start.ms
@@ -21,17 +36,19 @@ export default class Scheduler {
     let now = new Date()
 
     // set the target time
-    let targetTime = !start.timeOfDay
-      ? start.date
-      : new Date(
-          now.getFullYear(),
-          now.getMonth(),
-          now.getDate(),
-          start.timeOfDay.hour,
-          start.timeOfDay.minute ?? 0,
-          start.timeOfDay.seconds ?? 0,
-          0
-        )
+    let targetTime = (
+      !start.timeOfDay
+        ? start.date
+        : new Date(
+            now.getFullYear(),
+            now.getMonth(),
+            now.getDate(),
+            start.timeOfDay.hour,
+            start.timeOfDay.minute ?? 0,
+            start.timeOfDay.seconds ?? 0,
+            0
+          )
+    )!
 
     // if the target time has already passed today, set it for tomorrow
     if (start.timeOfDay && now > targetTime) {
@@ -58,7 +75,7 @@ export default class Scheduler {
     let delay = this.timeUntil(start)
 
     // set a timeout to start the interval at the target time
-    let timeout: NodeJS.Timeout = null
+    let timeout: NodeJS.Timeout | null = null
     timeout = setTimeout(function () {
       // Clear the timeout variable
       timeout = null
@@ -73,7 +90,7 @@ export default class Scheduler {
     // stop() function to stop the interval and timeout
     // stop(stopInMS) will stop the interval and timeout in stopInMS milliseconds
     // stop(stopHour, stopMinute) will stop the interval and timeout at the next stopHour:stopMinute
-    const stop = (stopTime?: TimeUntil): StopCancelFunction => {
+    const stop = (stopTime?: TimeUntil): StopCancelFunction | null => {
       if (stopTime === undefined) {
         stopNow()
         return null
@@ -114,11 +131,11 @@ export default class Scheduler {
     intervalMS: number,
     start?: TimeUntil
   ): StopFunction {
-    let delay = this.timeUntil(start)
+    let delay = start ? this.timeUntil(start) : 0
 
     // set a timeout to start the interval at the target time
-    let interval: number = null
-    let timeout = setTimeout(function () {
+    let interval: number | null = null
+    let timeout: NodeJS.Timeout | null = setTimeout(function () {
       // Clear the timeout variable
       timeout = null
       // start the interval
@@ -135,7 +152,7 @@ export default class Scheduler {
     // stop() function to stop the interval and timeout
     // stop(stopInMS) will stop the interval and timeout in stopInMS milliseconds
     // stop(stopHour, stopMinute) will stop the interval and timeout at the next stopHour:stopMinute
-    const stop = (stopTime?: TimeUntil): StopCancelFunction => {
+    const stop = (stopTime?: TimeUntil): StopCancelFunction | null => {
       if (stopTime === undefined) {
         stopNow()
         return null
diff --git a/tsconfig.json b/tsconfig.json
index 3288288..e8880f7 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -3,12 +3,11 @@
     "declaration": true,
     "declarationDir": "dist",
     "target": "es2022" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
-    "module": "nodenext" /* Specify what module code is generated. */,
+    "module": "CommonJS" /* Specify what module code is generated. */,
     "rootDirs": ["./src"],
     "outDir": "./dist" /* Specify an output folder for all emitted files. */,
     "esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */,
     "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,
-    "strict": false /* Enable all strict type-checking options. */,
-    "skipLibCheck": true /* Skip type checking all .d.ts files. */
+    "strict": true /* Enable all strict type-checking options. */
   }
 }