re potting now or later will cause stress that could risk the tree dropping any developing fruit anyways. So really the best time is when the roots need to have a new home. I assume that it is still in the sub par nursery soil. Personally I would repot now. Meyers flowers at all times of the year and with new fast draining soil your tree will recover quickly with improved vigor and should flower again pretty soon.

mike

There is no correct answer to this question. The best answer is to repot at any time with as little stress to the root mass as possible. I have done it at flowering time, with fruit on it etc. In my case, the best time has been Fall (as per advise from a local expert grower of citrus) when there are no new fruits or flowers. I keep my potted citrus outdoor because of our typically milder minters. The citrus repotted in Fall establishes roots all Winter long and the plant takes off like a rocket when spring shows up. YMMV for non-california climates.
But, if you see the plant declining, repot it ASAP.

If it is a matter of "life" or "death", I would do it asap.

If you think it will make it and you just want to change it at this time, I would wait as many here have said.

You forgot to say where you live, for that can make all the difference in the world.

Mike