Hi!
You do all adjustments idle adjustments wÃ*th the engine stopped. At least on air-bleed carbs.
But remember! All adjustments are not worth anything without having the tank mounted right (according to the tank mounting rule), the tank size right, prop size right, glow plug right and fuel right.
So lets go!

Tank should always be mounted with the centerline going through the carb when plane sits horizontal.
In your case a 300-400cc tank is right. Preferably Uni-Flow set-up.
Props in the range: 11x8,12x6,12x7,13x4,13x5,14x4 depending on plane.RAM, APC or Graupber "Sonic" are the best.
Fuel: 5-15% nitro.
Glow plug: OS 8 or Enya 3.But there are others equally good like Nova Rossi 3 or 4 or Rossi 3 or 4.