Microderm sessions are usually done every 10-15 days.. and they aren't that abrasive for u're therapist to give a gap of 4 weeks.. unless u had a reaction to the oxide crystals..
The only thing u shud be doing is cleansing u're skin really well.. and ALWAYS wear sunscreen..it's u're BEST friend if u're having any kind of treatments dones.
Do not scrub u're face or use any products with any type of "acid" in it for now..