Should I repot my stressed ZZ now, or wait for the new shoot?

If the rhizomes are sitting in water, I wouldn’t leave them there while waiting for the shoot to finish. ZZ plants store water in those thick rhizomes, and staying wet can lead to rot. Check them gently. Firm rhizomes and roots are a good sign. If anything is soft or mushy, remove the damaged parts and use fresh, well-draining potting mix in a pot with drainage.

Moving it back to soil can still be a stress, so keep the pot modest in size and avoid watering again until the mix has dried substantially.

If it’s stable and not actively rotting, I’d wait until the new shoot has opened and firmed up before doing another major change. A fresh shoot suggests it’s putting energy into growth, and there’s no need to disturb it just for appearances. When you do repot, choose a pot only a little larger than the roots, or keep the same size if it fits.

First figure out whether there’s an actual pot problem. If the current container has no drainage or the roots and rhizomes are crowded, changing it is reasonable. If it drains and the plant is secure, leave it alone for now. The wilted stem can be removed if it’s fully dead or mushy, but don’t cut healthy growth just because it looks a bit tired.

Don’t treat a calendar watering schedule as a rule for this one. After potting, let the mix dry well before watering again, and make sure excess water can escape. A ZZ can look thirsty while its rhizomes are still holding plenty of moisture, so check the soil rather than reacting to one droopy stem.