I think you have a few hours before it starts breaking down, in taste and effectiveness, especially considering the acidity of OJ. If you have a fridge at work, you could do what I do:
Cheap plastic bowls (Glad or Ziploc, etc).
Pitcher to mix the drink in.
Assemble the components in different bowls and take them to work.
I leave the blender, pitcher, and protein in my desk, but you could find a place for them or even keep them in your car if you had too. I also have a few bags of frozen fruit in our work fridge. When you want one, it is as simple as dumping it all together and running the mixer in it for a minute or so. Just rinse the thing off when you are done and you are good to go. Just make sure to rinse the pitcher as soon as you finish it or the drink turns into cement and is a bitch to clean out (soak it in hot water for 30 minutes).
Here is a shot of the mixer... you can get it at Costco for about $20.
I also recommed getting a mixer with at least 200 Watts of power, I bought a cheap one (100 wats) for work but it wouldn't cut through frozen fruits. I know that doesn't seem like a big deal to most but I like to use frozen fruits so it will give my protein shakes more of a milkshake feel to them.
LIL tip when mixing OJ and Protein powders. the acid makes them clump up like they do when they hit the stomach more so with casien based proteins ( thats why they digest slower think cottage cheese) anyway add a dash of baking soda to the OJ it'll fizz like a mother but that eliminates the acid and then the protein wont curdle when mixed.
As for the other question will it be good. Sure if kept cold no reason it wont be say half a day later. The protein may have began to degrad a little but Like Dave Barr has stated numerous times that degrading may actually be an aid not a hinderance. In a sense being a little pre digested for us.