Breast pump advice - when to buy?

Hi all!

FTM and getting so excited to meet our baby girl! We are moving to a new house this weekend and I cant wait to start actually preparing for her arrival.

I've chosen a breast pump on Amazon already and was about to order it to get my free Amazon gift, but then it occured to me that maybe I ought to wait. I've been leaking a bit since 18 weeks, but I know that that isn't necessarily an indicator that I will be able to produce enough milk to breast feed/pump/bottle feed. I do plan to do a combo, but ideally would like to wait to introduce a bottle until breast feeding is going well, so I'd hopefully have a bit of time after baby arrives.

I'm probably over thinking this, but here's my question: Would it be better to wait until after baby arrives to order my breast pump to make sure that I will even have a supply that warrants a pump, or would you recommend ordering in advance so I can pump as needed early on, even if I'm just storing milk in the beginning?

Edit: Money's not an issue one way or the other... just don't want to be wasteful!