Implantation bleeding usually occurs seven days after the last day of your last period. It can also range from 3 to ten days or no happen at all. Every woman is different. You can google it and get a ton of informative very helpful pages. I would suggest that is what you do. You will find definite answers that way.
yes...pms symptoms can be very similar to early pregnancy symptoms. Implantation can also happen around the same time you'd expect your period. Implantation bleeding is different from a normal period though. It's generally much lighter and spottier and doesn't last nearly as long as a period. If you have doubts as to if it's your period or implantation bleeding, you should take a test. Good luck..hope you get the answer you want.