how soon can I check?

Hi,
Welcome to ehealthforum.
If you were sexually active without protection (and if you are not on any regular birth control measures) during your fertile days/around your ovulation time, chances of pregnancy cannot be ruled out completely (for a regular menstrual cycle of 28-30 days, the usual fertile days would lie between days 8-18 taking day 1 as first day of bleeding). If cervical mucus has been fertile at time of intercourse, then sperms can stay alive for 3-5 days, and fertilize the egg once it is released at ovulation. Wait and watch for your periods. Visit your doctor/gynecologist for further evaluation if periods do not start within 10 days of expected period dates, or if you suspect chances of pregnancy, or if you develop any new symptoms. If pregnancy gets ruled out, and if you are not ready for pregnancy, but intend to remain sexually active, you should consider visiting your gynecologist to get started on suitable regular birth control measures to be protected (after your periods). Be regular with birth control use as instructed. Avoid having unprotected sexual contact if you are not ready for pregnancy.
Take care.