Can someone explain me how to have decent lane pressure with Tahm Kench top?

I mean, i only get good lane pressure when i get a lead, othwerwise i find it really difficult.

The lack of good waveclear is a thing that contributes to this, your only true waveclear is devouring a minions and spitting it on the wave, but you dont kill them off and you lose ALOT of mana.

So am i missing something or what? I also find incredibly difficult to apply 3 stacks and devour on solo lane, unless the opponent is braindead