@Billy40 AirBnB does not facilitate this type of process. The only way that you might be able to do this is to have the guest book a short stay, paying in full for those dates and then booking them for the additional dates off the platform (which is frowned upon, but then they are repeat guests and can book however they want to). You could also block the remaining dates and then have the guest request them closer to the dates. You then send a special offer that they pay for when they accept it. The only issue with this is that if they do not book, you will have had those dates blocked for a considerable length of time and may miss out on a booking from another guest.