Fight the impulse to immediately start working on the next phase. The best thing you can do is take a breath and let things settle.
Constant attention to the project and immersion in the requirements makes you ridiculously knowledgeable about what you’ve done and why. But along the way you lose touch with end users and stakeholders. Giving a site time to collect real user data and organically surface opportunities, will also give your brain time to reset. A little break can refresh you and help you spot the most important enhancements to make next (or bugs to fix).
No, you can’t afford to wait too long but you can spend a weekend reading a fantasy novel or a couple of days catching up on email. Just find some way to step out of project manager mode. If you do this, then you’ll come back to the project with fresh eyes.