Irregular period and testing

Pip • Pregnant with a little boy • c-section is booked for 4th July 2016 at 8am ✨
I'm very irregular at the moment. Last month I was due to start my period on the 25th March, however I started on the 1st April. I've been trying all month and have sore nipples etc. when do you think will be best to check? Shall I wait until the 1st may?