depends on MANY more things than you listed.. where you currently stand.. weight wise.. BF %.. and how cut you are trying to get and for how long.. are you running anything else with it.. clen.. T3.. ECA.. they all attribute to the factors.. technically.. var in dosages of as little as 2.5mg/day can elicit higher levels of protein synthesis.. which means your sparing or even building muscle.. but that's in a perfect state.. if your cutting.. your losing muscle due to it.. so you may need more var to overcome that.. T3 and var are a good combo and can be run together.. 20mg var/day is enough for up to around 100mcg of T3/day.. IMO.. i have done it and experienced no real muscle loss.. actually gains..
I would say 20mg/day is a good starting place.. 10mg/am-10mg/pm kind of thing.. if you feel like you are loosing some muscle.. bump it up to 30mg.. or 40mg.. or if you feel like you could drop the var lower.. go to 10mg/day.. var is a very multifaceted steroid.. it serves many purposes and is nearly flawless.. so have fun with it.. and let me know if you need any more help..