What Are The Side Effects Of Birth Control Pills If Taken Irregular?

Hello, a year back I was assigned birth control to regulate my period but do to an accidental misuse of it (I took 2 with too short a time period in between) I stopped taking it. I now have a package of birth control with the first two pills missing- it starts from day 3. Is it safe to use it again? When would be a good time to start it, if so?