Trying to concieve PLEASE HELP ANY INFO WILL HELP?

ok we are trying to concieve we started on may 14th, but i know im due for my P anywhere from the 18th to the 21 of may i do not ell like im going to start i alway feel like i am like 3 days befor i start do u think its to early to take a test this will be my 4th baby i never had any problems getting pregnant the first time always does it for me and what do u think my chances are getting preganat 5 days befor my P