In my experience you won't get the elite bonus for your return flights wit such a short turnaround. It'll take a couple of days for the mileage to post and then probably a few more for the system to update and recognize you as Elite (I believe this is done once a week on a Saturday). In any case, until nwa.com shows you as Silver - which will be a few days after your outbound mileage posts - you're SOL as far as receiving bonuses.

I had a similar situation when I reached Silver (but I wanted the upgrade privileges) - but was told by WP that there was no way to speed up the process. Besides, unless you're flying transcon or international the bonus is probably only a few hundred miles.

Congrats on earning Elite - once you have it you won't ever want to be without it!