Level up to 4 early if you want to start a win streak. Level up to 5 to try and continue the streak.
If you're weak in the early game, you can opt to save gold and lose streak instead.
At Round 3-2, level up to 6 regardless of your start. Put together the strongest team you can.
At Round 4-1, level up to 7. Roll down to stabilize your comp if you are weak. Afterward, save up to hit level 8 and complete your comp.
Gangplank is a nice transition unit for Urgot since his ability can produce extra gold, but Gangplank's ideal items are a bit different from Urgot. Urgot wants more base damage and scaling through non crit items, while Gangplank likes having crit and survivability items.