the ARs don't activate.. the androgen latches onto it and sends a signal to the body to do certain things. there are billions of receptors in the body. once the androgen latches onto the receptor its half life dictates how long it will take to completely dissolve in the body. so .. lets say u have a AR with a hormone sitting in it.. after a couple days when that molecule is gone that receptor is now able to accept another molecule. that said.. you don't just take a hormone and fill up all your receptors at once. it just doesn't happen like that.. its more like all the illegal aliens crossing the border.. they have to find a bus to get them to their destination.. until then they just float around in holding. same thing with andorgens.. they float around the body until they find a receptor to latch on to.
this is why you have to eat some androgens every couple hrs to reach a saturation point.