Need help on my plants? My first grow

This is my first grow I have two females but they are both in pots like the one in pic posted they both started flowering stage and I've read that you can't transplant during flowering stage? Will it mess them up or should I still transplant ? Or will they be fine to finish there grow in these pots ?

Transplant her into bigger pot, be gentle, she will be fine....

keep in mind they can double in size when they start flower

You'll be fine transplanting, handle root ball as little as possible. Thank goodness these plants aren't as fragile as a lot of people make them out to be. Most of the times it's poor growing practices that make them fragile.
A healthy cannabis plant is an amazingly resilient plant.