If he is going to be alone all day I think a friend is a great idea. Please don't put him in his new cage until the friend arrives. Most budgies are very social and parent raised and will therefor except a new flock mate pretty easily, but they are still parrots and they are still territorial, so it's important never to add the new bird to a cage the old one already thinks is his.
Now, if you have already put the bird in the new cage, here is how I suggest adding the new one.
Take the bird out of the cage, and move the cage into a different room. Replace everything in the cage if you can. Anything that has to stay (like food dishes) should be put in a different place. You can save the old toys to give back later, but I would replace them for now. The point is for the bird not to know he is in the same cage. Leave the cage in the other room if possible. If not, leave it in the other room until you can put the birds in in, and then move it back into the first room in a different place. Again, the point being to trick him into not thinking it is his old space. Be sure to have one food and one water dish per bird until you are sure they are willing to peacefully share dishes. The dishes should be far enough apart that one bird cannot guard both dishes at once.
Budgies in the wild travel in giant flocks. I do love for them to have friends. Some will caution that your budgie may not stay tame if he has a friend, and there could be some truth to that, but please keep in mind that if the bird is alone in the cage all day, there is small chance of him staying tame anyway. Of course if you do get time to tame them, budgies are one of the easiest birds to tame (still hard, still takes time) and you could tame the other one as well.