Too large a pot, no roots or spikes?

[greenpassion]

I have several phals and oncidiums in ceramic orchid pots, without a plastic net pot or slotted pot inside. When I first got each of the orchids, after the bloom went I repotted them, but I think I went way too big. The phals are in a bark mix, (classic phalenopsis mix) and the oncs are in a mix made for oncidiums. They all look ok, but I have no sign of root growth or spikes happening. Only one of my phals has roots showing up on top of the pot, and this one is sending out green healthy roots-but the others (I am thinking) are still too busy trying to fill the pot with roots. Could this be why I'm not seeing any roots up on top and around the pots? If this is true, should I go and repot all into smaller pots? A few days ago I ordered some clear slotted 4" and 5" pots, some angle moss and hydroton, and plan to change them into this anyway. I'm just wondering if the size of the pots is the reason why I'm not seeing roots