I generally have an idea of what I'm going to say, so I will title it beforehand. But if it doesn't fit afterwards, I will change it. Sometimes song lyrics, sometimes just a generic idea of what the subject matter is, or a weird quote someone said.
I rarely have a title in mind before I start. Usually, the titles are all over the place, too. They could be deep and meaningful, completely random, or bland and straightforward. Depends on how creative I'm feeling that day.
I title mine before writing...maybe next time I'll try doing it afterwards. Mine are usually just random thoughts...I'm learning to try and connect them with the entry somehow...haha...that way I'LL know what the entries are about at a later stage :P