How can I mark the area and shave without losing the mark areas??
Thank for your help! 
This is what I personally think you should do.
Leave the hair. Take the appropriate pencil (I think it has to be white or red) and a razor with you.
When you are uncovered, in front of her, mark out the areas and then dry shave them (or with just a tiny bit of water). That way there can be no question which areas need treating and she can also see the missed patches.
This was typical at my clinic. They would do the markings and then dry shave any spots I missed in shaving, and also the spot I left - I would always leave a small area to show the tech the thickness/density of hair so that she could adjust her settings if required.
I don’t think the tan can fade completely by September if you tan in June. I could be wrong though. If you want aggressive settings, don’t get a tan.
Agree with Stoppit&tidyup
Use a white pencil
And DON’T get a tan
Sounds good expect that she clearly asked me to come in shaved .
On the tan question so if i get some sun on my body during june july and part august when is the soonest i can be treated? How can you tell if youve faded enough. Honesstly though theyve been using yag on my white, unsunned skin the settings are hardly near high settings.
Wouldnt dry shaving just before laser be irritating?