As long as it's a normal pill (combined hormone, placebo week, all that stuff) you can be pretty late and still be ok. Generally, it's a good idea to take it within an hour I guess, but if you just do it at some time (like when you're brushing your teeth) that you'll remember every day, you'll be fine. Just as long as you remember to take it, for example, every evening.

So no, the exact time isn't important! You can be late by 6 hours before you have to worry. You can also take it early and you'll be fine.