Implantation bleeding ,

Okay I'm TTC baby #1 . Af was the 10th to the 17th . My periods are irregular 24-28 day cycles . I ovulated 18- 23 . Didn't BD on the 18th . But did BD 19- 23 . My question is , is it to early for implantation bleeding ? This morning woke up had a little spot of dark brown blood in my underwear . But when I wipe there's nothing & I Havnt seen anymore today ! Please Help !