It's 5 days. It's good to use a reminder service when you seriously consider
pushing a domain to auction. Easy to miss the deadline because we're used to
the 7-day deadline for offers.
But, it's OK. In most cases, push to auction won't really get you a higher offer.
Most domains are better off negotiating with the buyer.
Only push a domain to auction when it's a domain you don't mind letting go
if the price doesn't go up in the auction.
Sometimes, a winner at the auction may turn out to be a non-payer. The
Original bidder usually pays soon because he/she wants the domain.
Hope it helps,
DG
Domain Educator