kd u r right about the soil below getting too wet in larger pots. I personally would start out in small pots and look to transplant no more than twice and once pref. Transplanting isnt that much 'stress' if u do it correctly and there is less chance of u getting root rot or such that way. I start with pots about 10cm across and roughly the same deep and -depending on circumstances- i like to pot them up into 25cm pots before i put them on 12-12. but thats just me.