You can also choose to have the tempo change on a dime, or to have it gradually change from one tempo marker to another. A little off topic, and I forget where I read it, but there was an interesting suggestion from a producer that for a song that was generally the same tempo, you might still get a little faster by a few BPM for an upbeat chorus and back down for the verse. Rather than have a sudden tempo change (unless that's the specific effect you are going for), it's more natural to gradually build the tempo maybe for the last half measure of the verse, over a drum fill, and then when the chorus arrives, you are at the slightly higher tempo. I guess that's how a real drummer might naturally do it subconsciously. Cheers!