Depends on the cure time of the cement. However there isn’t much pressure on the piping so I would worry about it blowing apart as long as the joints are good.The longer you can wait for it to cure the better. I have turned the pump on and pushed wet cement into the tank water with no ill effects, more than once if that’s a concern. Glued the last joint cleaned up ,put the cement and tools back in the garage then let it rip. I use clear cement so a sloppy joint isn’t as visible. The blue rain or shine cement has a 20 min cure time IIRC. However one ut oh and it looks messy