Vennominaga the Deity of Poisonous Snakes is summoned as early as possible (when going first, as soon as traps are able to be activated at the start of the opponent's first turn).
Go first if you have the option. If you have Snake Rain it's obviously a good hand but what you really want to start out with is Nunu and any Reptile besides Nyami, Gardna, Mamba, or Vennominaga.
If you have Trap Tracks, you can use it to destroy Vennominon to pull and activate Rise and summon a ~9000 attack Vennominaga as soon as priority passes to you on your opponent's draw step. Melusine sets monsters to zero attack and Avramax acts as a sheild. If you make it to turn 3 and have a way to summon Black Mamba, then you can pretty much swing Vennominaga for game if Melusine set the targeted monster to zero. If you're having trouble, you can summon Baronne de Fluer with any 8 star (such as Melusine) and Lamia (but not on the turn you use Echidna's search effect, as it locks you into Reptile summons).
If you're going second and your opponent has a monster in attack position, you can use Snake Rain to send Nunu, Nauya, Aleirtt, and Keurse to go into the Draglubion-Numeron combo. If you're crafty and have the right cards, you can also summon King of the Feral Imps beforehand to make Numeron a 13k attack beater. If it catches your opponent off guard, that's game.
Decklist: ygoprodeck.com/deck/vennominaga-turbo-otk-325903