You should probably wait for 4.0 since that isn't enough coupons if they release new ninjas a couple of weeks after the 4.0 update. Only P2W benefit from new updates initially since they can enjoy it within the first two weeks such getting a super rare or close to in a treasure.

That is true but the longer any major updates such as treasures or ninjas arrive in our server, the gap between p2w and f2p is shorten by a small fraction. If you introduce a new update then that gap just gets bigger.