Pregnant???

I haven't had a period since March 8th. I was always regular until this. I took serveral tests all negative. Last Monday, June 20, 2016 I had dark brown spotting on 2 bathroom visits. Never enough to get on my panties, just their when I wipe. Then nothing, it did this one more time.

Could this be implantation bleeding? I don't want to get my hopes up for it to be negative.

So if it was implantation bleeding how long do I wait to test?