The window
Below ~5 weeks, residual swelling and a still-thickened epidermis hide what is actually missing, and re-needling recovering tissue adds trauma for little gain. Beyond ~10 weeks is harmless but the colour has begun fading, so you are rebuilding more than perfecting.
Adjust for the client
Fitzpatrick IV–VI and anyone with a hyperpigmentation tendency benefit from waiting toward the far end (8–12 weeks) so post-inflammatory darkening has fully resolved before more work. Dark-lip neutralisation cases may need each corrective round spaced a full 8 weeks. Fast, uncomplicated heals on fair lips can go at 6.
Book it upfront
Schedule the perfecting session at the first appointment. It keeps the client committed to completing the process and keeps the pair inside the ideal window rather than drifting to 'six months later', which effectively becomes a fresh session.
