How Should I Do This?

Hey all Sythe members,

I require some help on how to do a questing trade with Swift Feet. Well, he told me yesterday to get him 33 quest points in F2P and now I'm at 31 with 2 more to go (Going to do Black Knight's Fortress, 2 Quest Points). The initial payment for this was $15 via Paypal as a gift but he said he'll pay me $25 if i do it by 24 hours. Well, there is 5 hours left and I'm almost done so I was wondering if I should wait and contact him first and request the payment before doing the last quest as he was offline throughout the period of that 24 hours and then finish it off, or should I finish it off then give him the account back and wait for my payment. Which method will help me finish the trade with no hassle and not getting scammed in the end. If you have other methods, please share them!

Thanks for all your opinions