Interesting question this one. Well, because Lambo doesn't have a Sharingan, even if he can figure that bitting the thumb and etc will lead to a summoning, he can't make the swamp before the summoning is done as there is no time. His reactions aren't heightened thus he can't act as his opponents are acting.
This said, your move would be a great opening move if you didn't assume it happens before he can do the summon. Basically, by the time you'd figure he's going to do a summon and you do the hand seals, focus the chakra, etc etc for the swamp, the summoning would already be in the field and teno would be preparing his follow up move.
Because this is official, every detail matters. You should have performed the swamp assuming it would happen with the summoning already in play. The way you did it, yes, its a time frame breaking as its a breaking of the realism rule. Biting his thumb and doing hand seals and then slamming the ground can be the preparation for other techniques other than a summoning. You can't assume you know what your enemy is going to do unless you have some kind of increased perception (sharingan, Minato bios, etc) that would make your "guess" more accurate. Imagine it this way: you encounter a ninja you never saw before and he does hand seals...how can you know what he's going to perform if you don't know his abilities until he shows them?
