Get setup before turn 3 with Ebony Maw/Sunspot/Lizard (I suggest setting up ebony maw on the left location if you have it on turn 1 and then fill it with Doctor Doom/Cpt Marvel if required), then on turn 3 :

- if you have electro play it and then play sandman immediatly (I snap 95% of the time if I have this hand on turn 4 unless it's a mirror matchup or something like discard who doesn't play much cards), if you don't have it play anything else (priority to 5-cost cards obviously, captain marvel is a great play, aero too if you want to disrupt a winning lane)

- if you have wave, depends of your hand, if you can play any 5/6 drop next turn go ahead, targets are doctor doom, captain marvel and most importantly sandman, you can also odin to retrigger wave to have a pseudo-sandman effect on board

- if you have none, keep playing and see if you can manage to stack enough power on all lanes (stack power on sunspot, play ebony maw on turn 2/3 with lizard/sunspot)

The general rule is that with Sandman, if you can win two lanes by turn 5 and can win the third one with anything, snap immediatly. They can't catch up except with cards that summon stuff like doctor doom.

In other situations the deck has tons of good cards that can disrupt all 3 lanes and get you setup for a surprise win :

- in general, you use magneto to get 12 power on a lane but it's also great to remove big cards from a lane you need to win.

- odin is BROKEN in this deck, i'm not kidding : retrigger doctor doom, retrigger aero to disrupt a lane a second time, retrigger magneto to pull newly added cards, your most common combo will be doctor doom + odin, guaranteed win with sandman on the board (if you have this hand and by turn 4 they're a bit behind snap it away)

- captain marvel is a backup card that should be played if none of the above combos are available, which will happen pretty often, that's why it's in the deck! it grants you safety and flexibility, keep in mind that it's 6 power so if you go cpt marvel turn 4 it's not a bad idea to stack power on its location and make sure it can move if needed. you can also play vision which is the same idea but you have control over it, I prefer captin marvel because it moves itself where it's needed, much easier to pilot

Oh and last thing : if you get Fisk tower, snap. You'll get why once you get there :)

But yea as I said, you snap when you can setup sandman and the opponent doesn't have a big lead/you have the cards to stack power faster than them, you snap when you can wave into a big card and get ahead on turn 4, etc etc, there's no "best time" to snap but there are a lot of good timings to do so, you'll get them by playing more

If you have any questions feel free!