@Becky174 That doesn't sound like a great idea. I'd decide on prices now (if you want to have different prices for weekends or holidays, take that into account) and set your booking window for now for 3 months into the future. That will give you 3 months of hosting at the prices you set, and you can then set new prices for the months after that if you find you're not making enough profit, getting low life guests, or not getting bookings because it's too expensive.
Just remember that each day, one more day will open up in the future to keep the availability at 3 months.