the best time to repot is..
right now.
I would do it like this:
flood the fishbowl.. pour in some water until water is right up to the surface,
to totally loosen up the moss and make the roots easy to remove..
reach into the bowl and grab a big handful of VFT and moss and roots.
gently wash away all the soil from the roots with some kind of fine spray..
a gentle hose spray, maybe the spray thing on the kitchen sink..
(dont worry about using tap water for something like this..tap water is only bad if a CP is watered with tap
all the time..it wont hurt a thing if you simply wash off the roots with tapwater.)
another way to wash off the roots is to simply dunk the plant into a (clean) bucket of room-temp tap water and swish it around a bit..
you will already have a pot, tray and media ready. (peat moss or Long Fiber Spagnum..or peat and sand if you want to try that..I would recommend pure peat or pure LFS)
stick the roots into the new pot, and gently work in the moss around the roots..
one trick I like for repotting..
fill the pot full with the media first..
poke a wide hole in the middle with your fingers..
so media is still up against the side walls of the pot..
stick the roots down into the hole..
press the moss into the roots from the sides..
fill media back in.
water the pot, using the GOOD water now..(rain water, RO water, or distilled),
water from the top to let the media fill in around the roots and fill-in any air bubbles that might still be in there..
sit the pot in the new tray, fill the tray with water and stick the plant out in the full sun..where the leaves will quickly fry to a golden brown:
http://www.terraforums.com/forums/showthread.php?t=111701&page=3
which is ok..
being burned is still better than being in the fishbowl..
Scot