Unless it's an unusually heavy infestation it would probably be best to wait until after she lays the eggs. I strongly recommend getting a Vet's advice, though.
Personally, I'd be a bit leery about "gravid" being used merely for a selling point, if you know what I mean. Especially if the main reason you're considering buying it is because it's supposed to be gravid. Someone in your other thread asked why anyone would be selling a gravid snake. I believe I would wait until after she laid her eggs before I sold her. You can sell one snake now or sell many more later, making more money.
However, it could very well be legit. They may (1)need the money now, (2)not want to fool with the eggs due to lack of time or lack of proper setup, (3)etc... Many dealers just want to make a quick turnaround and not fool with breeding, raising.
Check out the seller as much as possible. If they regularly post on a forum, read their posts, old & new. A person's posts can tell a lot about them.
I hope things work out for the best for ya!
Take care!
Mike
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It is said that 1 out of every 4 people are mentally unbalanced. Think of your 3 closest friends, if they're normal, then it's you.