yet a other bad answer
If you press a when it hit 0 I can almost gurAntee you will not get the right delay
To find when you press a you must do your own calibration. I recently got an ar dsi and calibrated that I have to press a at 1.6-1.9. it gonna be a long precedure.
If you not rng to capture pokemon with the 100 code than you should really not rng with an ar because it would be easier not to.
This makes an excellent point, and I couldn't agree more. You will always have a different delay when using AR as opposed to not having an AR. For example, when I'm using AR, my average delay is 484-485, but without an AR, it's 501. So you need to calibrate the AR's delay on RNGReporter.
On top of that, you also need to figure out how long it takes the AR to load the codes until the screen actually turns white and loads the game. For me, it's around 1.4 seconds, so what I do is subract 1.4 seconds from the first timer, and add 1.4 seconds to the second timer.
Hopes this helps, post your results afterwards. :)