HennaTraditions - Henna Traditions
Ideally, you should get your Mehendi done 2 days before your wedding day, to get the optimum color. It takes 36-48 hrs for Mehendi to reach its peak stain.
Also, if there is a Mehendi ceremony or there are other guests, relatives who will also get their mehendi done, then it is highly advisable to get your mehendi done a day before or towards the early part of the day, before the guests arrive. This is important because Bridal mehendi can take upto 3-8 hrs depending upon design and complexity and you need to be relaxed.

You can come in for a complimentary  30 minutes consultation, any day before the Mehendi night, so as to select your designs in a leisurely way. As a Bride, you are sure to be preoccupied with a lot of things on the Mehendi night and alongwith other distractions you might not find time to select the perfect design for yourself. A Mehendi consultation is highly recommended.

Get your waxing, pedicure, manicure done before your mehendi day.
Do not apply any lotions or creams on the day you want mehendi done, before or after.
Wear comfortable clothing, so as to be able to sit comfortably through.
Stay well fed.