After you receive a waiver for ROFR, Disney still has to send the title company an estoppel letter. After they receive that letter, they can draw up the contract and mail it out to you and the seller. The seller may need to get their copy notarized, and you need to get a cashiers check. After everything is returned to the title company, they'll close (just like closing on a house) and send the new deed to be recorded by the county, as well as send the transfer paperwork to Disney. If you don't already have a membership, they'll create one, transfer the contract, and load the points. So, there are multiple steps, each with different people responsible for moving the process along. If you seller takes a while to sign and return their documents, the timeframe is extended by their inaction.
Generally:
ROFR: 28-32 days
Estopple: 14-21 days
Closing documents: 1-4 days
Parties return their documents: ?????
Closing after documents returned: 1-4 days
Membership created: 10-14 days (Credentials are available by calling at this point)
Credentials come in the mail: 7-10 days
75 days is a good bet, but it could be anywhere from 60-90 days depending how quickly the buyer and seller move.