Both, and each requirement is validated separately when determining your earliest possible booking date for each day. Whichever would give you the earlier booking date trumps.
As a reminder, here is the timing per the dedicated LL thread:
I believe that if you cancel your leading reservation before you become otherwise eligible to book, they could be removed by the end of the day when you cancel your hotel reservation unless you book a new reservation that makes you eligible.
Right now, the 8 day cancellation window isn’t in effect (it’s still 5 days) so you could in theory use a leading reservation (which I do not advocate for ethical reasons). But starting January 1st, you will have to cancel before 8 days so leading reservations won’t work unless you are prepared to pay for the leading reservation.