They do have until August 15th.
I think his ELC will kick in next year even if he's signed any day/moment. He might be signed to an AHL ATO to join Laval. They do have 3 games left. Maybe he'll get in a game. Or maybe it'll be like they did with Primeau years ago and just have him be around the team and just get practices in.
Last year, Struble was signed 5 days after his college season ended. If Tuch is signed now, I don't expect it to be 5 days because Struble signing was in March, so they had time. With Tuch, they don't if they want him with Laval or Montreal. Both their regular seasons are almost done.