Health

I'm kinda really confused I'm trying to conceive but my period starts September the 6th which is this month and it will end September the 11th and they said to test for ovulation on DAY 14th which means I should ovulate on the 19th of September but I was wondering could I have sex before the 19 like say I have sex on September the 15th and the 16th of this month could I still be able to get pregnant or? What?? And it's before the 19th of September.