Tmi Implantation bleeding?

So yesterday at the beach I went to use the restroom. When I wiped after I finished I noticed a little streak of pink on the toilet paper. I also started to have light cramps afterwards and so I decided to put in a tampon just in case. Well later when I got home I took it out and there was only a very very small amount of dark brownish blood on the tip of the tampon. I've had no more bleeding since and I don't ever spot before my af which is due on the 8th. Is it possible that this was my implantation bleeding and if so how long should I wait to take an early response test?