When to repot Miltassia Shelob 'Tolkien' ?

[RandomGemini]

This thing needs a repot. Check this out:



It has two spikes blooming and I believe it's growing a third spike, also, nearly every pbulb I can see on this plant, seems to have a new one growing off of it and I think there are about 12 pbulbs on the plant now... and it's packed into a 4 inch pot.

When's the best time to repot these? I'd like to enjoy the blooms on this one for as long as I can, but at the same time, this thing is so tight in the pot that I can't even tell what medium it's potted in.

Thanks!