Personally...I would work on ridding the plant of any pests now. If you have scale/mealies/anything munching on your already weak plants...these pests will further weaken the plants and/or cause other problems.
I agree, I missed this problem! First get rid of the bugs!
Nicole
My first question, before deciding, is how large of a division are your plants?
Some oncidiums do new growths and spikes simultaneously, and if there are enough old growths to sustain it, I agree with Ross and would simply wait, as the roots will come along soon.