Divide day block/cell to more blocks/cells

It's possible to set custom cell size using the following settings:

dp.scale = "CellDuration";
dp.cellDuration = 240;   // 240 minutes = 4 hours

See also:
https://doc.daypilot.org/scheduler/time-cell-duration/

Just note that the hotel room booking tutorial (https://code.daypilot.org/27453/html5-hotel-room-booking-javascript-php) uses dp.scale = "Manual" and the cells are generated manually in loadTimeline() function. See also the "Check-In and Check-Out Time" of the tutorial.

Thanks a lot! I change it to 360 // 6 hours
Then change .addHours to 6.
dp.timeline = [];
var start = date.getDatePart().addHours(6);
It is working, but it seems its loading calendar really slowly

What DayPilot version do you use?

Since 8.1 SP8 it should be able to handle a very long timeline without bigger performance problems:
http://javascript.daypilot.org/daypilot-pro-for-javascript-8-1-sp8/

The rest of the Scheduler shouldn't be affected much because by default it uses progressive rendering for cells and events (so it doesn't depend on the absolute grid size).

However, if you see a performance drop you may need to use a shorter timeline (e.g. 1 week instead of 1 month).