Hello @Rachael362
If you're having trouble juggling arrivals and departures and you are just starting out, it is wise to leave Instant Book off.
The worst thing to do on Airbnb is cancel a reservation - you get fined, your calendar is blocked, your stats go down and your listing will appear at the end of a search.
I had IB on in my first week when I started out and quickly took it off as I like to plan my arrivals and take the time to communicate with prospective guests first so that I can be sure that my listing is a good fit.
You can also programme a delay between departure time and arrival time for your listing to avoid having back to back bookings.
In host mode:
==>Listing
==>Pricing and availability
==>Calendar availability
==>Preparation time - you can block 1 night or 2 nights before and after a reservation
There is also the possibility of blocking off days on your calendar to avoid last minute bookings in that guests can request to book giving you the host Advance notice - ie 1 or 2 days before their planned arrival time. This feature is just before the preparation time in the calendar availability if you want to add this.
It's important to do what suits you and your lifestyle and not to feel pressured to accept IB as cancelling a reservation is the worst scenario!!
Good luck!
Joëlle