All at once or split is find.
50mg at one time:
50mg, 8 hrs later 25mg, 8 later 12.5mg, 6.25
If you spread them thru the day you actually have less in your system for a little while but eventually would end up the same or more.
But I've never noticed any difference between the two. Also never noticed anything by taking it before gym but some guys seem to.