feat: add optional startTime prop to BookerPlatformWrapper (#22731)

* feat: add optional startTime prop to BookerPlatformWrapper

- Add startTime prop to BookerPlatformWrapperAtomProps interface
- Allow users to override calculated startTime from useTimesForSchedule
- Maintain backward compatibility when prop is not provided
- Add JSDoc documentation for proper usage

Co-Authored-By: somay@cal.com <somay@cal.com>

* feat: add custom start time support to Booker component with date object input

* feat: update documentation and added changelog

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: somay@cal.com <somay@cal.com>
Co-authored-by: Somay Chauhan <somaychauhan98@gmail.com>

.changeset/dull-carpets-help.md

@@ -0,0 +1,5 @@
+---
+"@calcom/atoms": patch
+---
+
+Added new startTime prop to the Booker component that allows users to decide the first available date when the booker loads

docs/platform/atoms/booker.mdx

@@ -90,6 +90,7 @@ Below is a list of props that can be passed to the booker atom.
 | customClassNames           | No       | To pass in custom classnames from outside for styling the atom                                        |
 | month                      | No       | The exact month for displaying a user's availability; defaults to the current month                   |
 | selectedDate               | No       | Default selected date for which the slot picker opens                                                 |
+| startTime                  | No       | Custom start time for the Booker that allows users to decide the first available date. Accepts JavaScript Date object or date string in format `YYYY-MM-DD` (e.g., `"2025-08-20"` or `new Date("2025-08-20")`) |
 | hideBranding               | No       | For hiding any branding on the booker                                                                 |
 | isAway                     | No       | Sets the booker component to the away state                                                           |
 | allowsDynamicBooking       | No       | Boolean indicating if the booking is a dynamic booking                                                |

packages/platform/atoms/booker/BookerPlatformWrapper.tsx

@@ -57,6 +57,7 @@ export const BookerPlatformWrapper = (
     isBookingDryRun,
     handleSlotReservation,
     onTimeslotsLoaded,
+    startTime: customStartTime,
   } = props;
   const layout = BookerLayouts[view];
 
@@ -220,7 +221,7 @@ export const BookerPlatformWrapper = (
       : undefined;
   const { timezone } = useTimePreferences();
 
-  const [startTime, endTime] = useTimesForSchedule({
+  const [calculatedStartTime, calculatedEndTime] = useTimesForSchedule({
     month,
     monthCount,
     dayCount,
@@ -228,6 +229,12 @@ export const BookerPlatformWrapper = (
     selectedDate,
   });
 
+  const startTime =
+    customStartTime && dayjs(customStartTime).isAfter(dayjs(calculatedStartTime))
+      ? dayjs(customStartTime).toISOString()
+      : calculatedStartTime;
+  const endTime = calculatedEndTime;
+
   const [routingParams, setRoutingParams] = useState<{
     routedTeamMemberIds?: number[];
     _shouldServeCache?: boolean;

packages/platform/atoms/booker/types.ts

@@ -83,6 +83,7 @@ export type BookerPlatformWrapperAtomProps = Omit<
   isBookingDryRun?: boolean;
   eventMetaChildren?: React.ReactNode;
   onTimeslotsLoaded?: (slots: Record<string, Slot[]>) => void;
+  startTime?: string | Date;
 };
 
 type VIEW_TYPE = keyof typeof BookerLayouts;