They start as soon as the embryo has implanted into your uterus. They may be very similar to your normal menstrual symptoms. Of course, everyone is different. Some know as soon as the embryo is implanted, and some have no idea until they're 2 1/2 months along.
If you are trying to conceive, then I would suggest to continue the process of conceiving. If your period does not arrive I would get a test (doesn't have to be the expensive ones.) in all reality, that is going to be your determining factor.
Conceiving after birth control is also different for everyone. Stopping birth control can have a huge affect on your menstrual cycle. It can be on time...Or it can delay it until it stabelizes. I know of people conceiving because they missed 1 week of the patch. But, like myself, I had to have my menstrual cycle after birth conrol, induced with a special hormone pill.
I hope that this helps just a little or at least answers some of your questions..
Good luck!!!
Sarah