Every resort system has its own RULES. Plus, what was valid 15 or 10 or 5 years ago, MIGHT not be valid for a new owner or a resale buyer today.
Too general of a question for the REAL info you seem to want.
And inside of a system, different resorts would have rules differences, too. Like some Wyndham resorts have either FRIDAY or SATURDAY as a checkin day .... then there are other Wyndham resorts which include SUNDAY as a checkin day. And other resort chains, there might be just ONE day as the checkin day.
So, who can book when based on direct buying or resale buying ... not a general answer. But that could change tomorrow.
PS Wyndham points system do NOT currently have different booking windows for direct buyers vs resale buyers.