Help!!!!!!

I know this may seem like a dumb question but I'm new to all of this. We plan to start TTC in August and I've been tracking my period for a couple years now. I know the "I deal cycle" is to be on a 28 day cycle but mine hasn't consecutively been that long. It's been around that long for a while but it hasn't been precise. Is this ok or will it cause some trouble while TTC? Thx ladies