I did Cellfina 5 weeks ago. I have a lot of red-purple spots. How quickly can I start using hydroquinone treatment?

IPL laser, and topical creams such as biocorneum are a better choice.  Arnica cream for bruising can help as wellResults can be seen in as little as three days post-op. Most patients report some soreness, tenderness, and bruising, which should resolve within a week. 90% of patients reported no bruising after one month. To ensure the best results, a compressive garment should be worn for 2 weeks post-treatment.

It is normal to have discoloration at the access sites of the small knife used to break the bands (that cause the dimpling). I suggest Biocorneum silicone gel. This should be applied to these site twice daily. Biocorneum will help reduce the redness. Hydroquinone acts on the cells that make pigment. Unless these sites are a lot darker than your usual skin color, the hydroquinone may not make a difference in the outcome. 

Addressing the structural cause of cellulite involves surgically releasing the connective tissue bands that tether skin and create puckering. While Cellfina is a minimally invasive procedure, the procedure does require access points in which a needle-sized microscopic scalpel is used to release the connective bands at specified depths. These puncture sites can take time to heal, and there can be evidence of bruising for several weeks or months as everyone heals at their own pace. Some patients benefit from using arnica gel/cream for post-procedure bruising and swelling. As hydroquinone treatment helps with hyperpigmentation, it may help to diminish the appearance of the puncture sites once they are closed. It is important to consult your board-certified plastic surgeon regarding any questions or concerns as you are healing from the procedure. Good luck in your recovery!