Transplanting During the Earliest Stage of Flowering

I'm growing 2 plants in pots outside. I did have three but my plants just started flowering yesterday, and today I discovered a male, and of course I had to get rid of it. I only had two 10 ten gallon pots at the start with my other pots all being 5 gallons or less. So like a fool trying to save money, I started growing my third plant in the 5 gallon pot instead of buying another 10 gallon pot. Unfortunately the male plant I just discovered was in one of the 10 gallon pots. Of the two remaining female plants, the one in the 10 gallon pot is doing great, but the one in the five gallon pot is a different story. It is now about 3 feet tall, has outgrown it's pot, and definitely needs to be transplanted. I don't know yet, but there's the definite possibility that it has become rootbound because I can see a few roots coming out of the bottom of the pot, unlike my other remaining plant it needs contstant watering or it wilts, and vertical growth has stopped almost completely. I already know that if at all possible, transplanting after the plant has began flowering should be avoided because of the great stress it can cause, but I'm hoping since the plants have only been flowering for two days now, I could go ahead and transplant with minimal stess on the plant. What do you think? Anybody out there got any answers? I definitely need help.

If you transplant properly, the stress caused should be minimal. You're better off doing it now before it progresses any further.

Do it just be really carefull not to damage any roots.. last year I transplant a couple days after pre flower... After transplanted to me my lady loved it...

I've transplanted as late as 4 weeks into flower, from a 5 to an 8 gal...she never missed a beat.

What I have NOT done is to transplant out of a 5 gal by myself, b/c you really need someone else to grab the container while you hold the plant.

you should be fine. an alternative to a full on, potentially traumatic transplant would be to simply place the container on top of a mound of new soil - the more soil the better. the roots will grow out of the bottom of the container into the new dirt - I've had unintentionally good results with 5 gallon containers on the ground, even in shit ass clay.