If you were tweezing/plucking with any frequency, then you should begin your electrolysis treatments ASAP.
You can’t wait for all the hair to grow back because some will shed before some others have a chance to grow back from the tweezing.
This is what I tell clients who have tweezed: How often you were tweezing is how often you should have a treatment. The exception to that is daily tweezing - and in that case you can have treatments every 5 to 7 days. The length of time spent tweezing in 5 to 7 days is about how long your appointments will be for the first month or so. For example, if you were tweezing 3 times a week for 5 minutes each time - then your weekly appointments will start out being about 15 minutes. If you were tweezing for 10 minutes every day then your weekly appointments will be around one hour to begin with.