When to take Pregnancy Test?

Brycelynne
So the last two days I've had senestive nipples, like once I let my little lady friends out of a bra and put a t-shirt on (braless) they are sensitive to touch or anything against them. Also, they are super rock hard.  This is out of normal on my girls. 
I have been off birth control for 3 weeks now. I am TTC, but yet not 'trying' to obsess over TTC because I don't want to be let down. I've felt a little sick/dizzy in the mornings I've noticed but not too bad. During the week I had serve cramping in stomach, back and legs.  Which to me reminded me of my period cramps but nothing came.  I'm suppose to start my period on Wednesday.. But it could be irregular due to being off birth control now.. 
I'm unsure what to do, if I take a pregnancy test now which my first response site claims I can would it be accurate.