sex on before period???

if we have sex on the <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> of my period does that lessen our chances of conceiving this cycle? Sorry if it's a dumb question, just trying to stay hopeful is all... I'm 4 days late on my period already but keep getting negative test results, so we thought why not keep BD for the fun and Hope lol!