could this be true?!!

My period is suppose to begin in 2 days! My hubby and I have been TTC for a while. I took a First Response Pregnancy test this morning and it says that I'm pregnant!!!!!! I'm SO excited, but my periods are usually irregular, so I'm scared this could be a false positive! Has this ever happened to anyone? 
Can anyone tell me their experiences with First Response? 
Thank you for your help :)