They probably wont see much this early, they may notice the womb lining is thicker but it i think it is thicker before af anyway.. with my last preg they scanned at 4weeks 3days which was far to early! i think between 5-6 weeks is best
Dont worry hun, youl get a scan in a couple of weeks after that bfp on saturday!
Oh i nearly forgot to say good luck at your scan, hope everything is ok xxx