If you mean this Monday, which was two days ago, then no it is not possible for the egg to be implanted already.
The egg takes 3-4 days just to get to your uterus. Implantation occurs anywhere between 6-12 DPO, with the average of 9.
If you are actually 9 DPO and you meant the previous Monday, then it is possible. However, the problem with implantation bleeding is that you can't tell if it is random spotting of IB until you get a HPT...so try not to go crazy looking for signs. Also, IB is actually pretty rare, so most likely it is just random spotting (pregnant or not).