Can It Be True?

I'm due for AF on Wednesday, but I broke down and tested today. And I got it!!! My BFP, finally! That second line popped up within seconds of me taking the test and was super dark! I've been having light cramping and I'm kind of nervous. I'll be 4 weeks on Wednesday, according to the app. Is it safe to say because I got my positive so fast that the egg implanted already? FTM here, had a MC last April, so I'm all paranoid.