I really don't want to give you any wrong information, what works for me may not be perfect for you.
Googling "Epiphyllum care" will give you tons of general information, here is the cultural info on Epies.net to get you started.
http://www.epies.net/cgi-bin/e...
I usually place my Epis either in full sun or somewhat protected depending on the type of Epi, and if they are acclimatized to full sun. The soil needs to drain freely, but I don't find them to be too fussy with what I use.
Your plants look fine, I would just let them grow and fertilize with a 20 20 20 or similar while in active growth. They will not need to be repotted for a couple of years, as they still have lots of room in their pots. When they will bloom? That depends....
Happy growing.
