If you are happy enough to have just a coffee and maybe a danish for breakfast, you can save time by waiting to buy it until you get in the line waiting for rope drop. You can send someone to get refreshments for your group, or take turns. As far as I remember, there are always coffee/snack shacks near the place where you line up after the bag check, but outside the turnstiles. **
We discovered this by accident when we tried stopping at an I-Drive McDonalds for coffee on the way to the parks, and DW was extremely annoyed that the drive-thru people "weren't sure" if they had any milk for coffee!!!
If you wait til the park opens and try to get a coffee inside the gates, you may be delayed because of (a) the opening show, and (b) the tidal wave of people bursting into the park when the show finally ends.
This strategy is good if you really want to make every minute count, and if you dislike the free coffee in your hotel room and want to buy something better elsewhere without losing any time.
[** - I think that I can spot the little coffee shacks in the google maps satellite/bird's eye view, but perhaps someone with more recent knowledge can confirm]
