So I'm trying to conceive a child, I had unprotected sex and my partner did ejaculate inside me... the thing is I got what I think is my period the very next day but its very early ? How long should I wait to try again ?

Wait to do what ?

If you are trying to conceive then you would have tracked your ovulation properly, ( not with online charts) but using medical tests such as body temp to know when you ovulate. Then you time sex slightly before estimated ovulation.

So if that is what you did this month, then you just wait till next months ovulation dates.

If you are just jumping in the bed having sex, do it again and again and hopefully you will get there at some point.

Next is it a real period, or just spotting ?

Its very light my period wouldn't be due for another 3 weeks though its very early

Very light can be spotting and happens at times in pregnancy.

If your period is not due for 3 week there is nothing at all you can do now but wait.
Wait and see if you get the period, if you miss the period, wait two more weeks to do a pregnancy test with first urine of the morning