Rd-4 is May 07 - May 20
For the smooth and successful negotiation, please send offer to your opponent as early as you can.
That way both of you will find the maximum flexibility, even more if both of you are in different continent with difficult time zone to deal with.
If 1 side had sent multiple offers but their opponent never replied until Thurs May 16 (which is two-thirds of Rd-4 timeframe or 5 days before deadline), they can let me know TD by sending copy of their chess com message/ conversation, then TD will declare forfeit win.
If a player is forfeited, due to zero communication with opponent, or fail to show up in agreed schedule (without explanation afterward), he/she will be put in Pause in next Round until he / she contacts back TD (Tournament Director) explaining.