About how long before should I stop smoking marijuana if it is needed too before lipo vaser?

Smoking of any type and use of any #tobacco or #marijuana product may affect your #healing and the end result of your surgery. It's best to call your plastic #surgeon to better clarify. It is encouraged to refrain from cigarettes prior surgery and post op in order decrease the chance of complications and promote better healing. 
Typically, stopping a minimum of 2 weeks prior to the surgery date is usually recommended. However, the farther in advance prior surgery and the more time after the procedure, you can avoid #smoking, the better it may be for your surgical #outcomes and your overall #health. It's also very important to implement healthy lifestyle choices to not only prolong your surgical results, but most importantly, to reduce your risk of illness and disease which will impact your health. If you find it difficult to quit smoking, speak to your physician who can provide information and programs that are properly designed to help you quit. 

You should stop smoking marijuana at least 2 weeks prior to having vaser lipo, or any surgery due to the nicotine substance in it. Edibles and such should also be stopped.

Whether there are indications for the medicinal use of marijuana is a topic beyond what warrants discussion here.
The people of California may believe so but the DEA does not.
Considering the strength of current marijuana sold I would  call 3 to 4 joints heavy usage.
Each plastic surgeon will have their own opinion about this.
Since you're scheduled to have surgery you must already have a surgeon you're working with.
You should ask him or her what their views are since they will be taking care of you.
I personally don't care if people use marijuana before or after surgery.
Other than the smoke of the marijuana which causes lung damage and put people at risk for lung cancer marijuana by itself does not lead to significant increase in surgical complications.
It is primarily the nicotine in tobacco use that as a substantial detrimental impact on surgery.
Check with your doctor, hopefully a board-certified plastic surgeon to see what his or her views are.
Best,
Mats Hagstrom M.D.