You can either knock them out during the day, or you can knock them out the moment they wake up at night. It is far safer to knock them out during the day because they will be sluggish but you will have less time to starve them unlike if you tranq them after night. Note that more than likely you will have it wake up because no matter what when night hits they will automatically wake up which is why you must starve them before you tame them. This makes them a challenge to tame for some people. However with some patients and practice you will get the hang of it.
People say that is easy taming on day rather than night, but thats not truth because they always wake up, no matter how much torpor they have at 20:30 in game, that will cause you to lose all your taming process, I always tame these guys by starving them 2 times and then the 3rd knockout I put the food on its inventory, thanks for reading
Tame the mega during the day! It is extremly slower during the day due to wanting a rest. It is a very strong dino, it has been tested to be even stronger than the allo! Be careful if you tame it at night ;) caw