I'm not sure how to find the deadline
rvugt told me it was when play started, but I think he meant the deadline for sending picks...
Check out the Tennis Tipping FAQ/Guide
and look at commitments section
For all TT Tournaments there are two deadlines for signing up.
The first deadline is the Sunday (week before start of tournament) before Qualifying starts at 6PM CEST. This is for singles only. Any player who signs up for singles after this time is considered a late entry. Late Entries go at the bottom of the entry list following players without ranks. This is to encourage players to sign up and commit to a tournament early to know if it is worth running.
The second deadline is normally the Friday before Qualifying starts at 6PM CEST. This is for both doubles and singles and is the cut off for being able to join a tournament.