Please do *not* cycle a tank with rainbowfish, whatever you do, especially Boesemani. They are very O2 intensive fish and the nitrites will kill them outright. Also, most of them carry columnaris and will break out in threads under the stress.
As for how many Boesemani in a 35g -- IMO -- NONE. They are schooling fish and need to be kept in schools of six or more. They also get 4-5" in size and need space to swim. A 35g is too small for rainbowfish of that size.
After your tank is cycled and assuming your tank is at least 36" long, you could consider Neon Rainbowfish, Melanotaenia praecox. They only grow to 2.5-3" in size.
Roan