First of all the lag you described isn't legal.......both players must lag their balls at the same time......this isn't a batting card line-up.......you and the other guy strike the ball at the same time.
So the next time, just say "After you..." and don't lag or else pick up his lag ball and hand it back to him and say..."Let's try to get it right and do it again.....at the same time."
Don't let someone break the rules and then complain you don't like the way he does this late lag. If that player inadvertently strikes the cue ball on a practice stroke while preparing to take the shot in your match, do you say "Never mind....just keep on shooting."? You better had not because it's a rules foul and the break is also regulated by the rules when using the lag to determine who has the break.
You can always just stay down in your shooting stance with the other player as if you were going to lag but don't.......Yup, just stay in your stance or stand up, stretch and resume your stance again to shoot...and do that again and again....3-4 times if needed....and then say to the other guy if he hasn't caught on yet....turn and say, "Whenever you're ready, maybe we can complete a legal lag by lagging both balls at the same time otherwise we can just do this all night. If you did that to this guy, I betcha you'd get into his head and mentally, he'd start the match annoyed and really off his game. In his mind, he's thinking what a SOB you were even though he's the cheater......then....and this is key......later in the match, when the time is right, you just mention to him on the way to the table after he missed a shot...."Sorry about how our match started with the lagging issue but I just knew you'd want to abide the rules. That a burr under his saddle and his horse will definitely buck again after you hit him with that mental body shot.
Just like in golf, the rules can be your friend or your adversary.....so why not use the rules correctly which would be to your advantage? Tell others to do this to the fellow. he will get rattled and annoyed and his inside edge, i.e., illegal lag, once it's removed from his repertoire of tricks will annoy him to no end.
Why is it an advantage to lag last......because you get to see when your opponent lags too softly or hard and you can tell the cue ball will come up short or long from the head rail......and then you get to lag a ball to beat your opponent's mistake. When I lag last, I usually win the lag unless my opponent has hit a great lag shot which does happen. But by lagging last, you just know how hard to stroke the cue ball when your opponent hits a bad lag and it happens a lot more than you might otherwise imagine....especially if you play APA on 7' tables. So when you get to lag after your opponent has lagged, then you get to judge his lag speed that's very important since table cloths tend to have varying speeds, and you either gain information or else capitalize on their piss poor lag. when it occurs.
So don't let this guy continue to flaunt and violate the rules from performing an illegal lag to determine the break. If he doesn't like doing a legal lag, then just tell him...."OK, we'll flip a coin to decide." but don't let him keep breaking the rules to his obvious advantage.
Matt B.