Most of the things i have read/seen - mention 3 weeks before a soil sample.

Personally i would wait a little longer - hate to bother getting a sample and then have it skewed by the starter fertilizer...

If it was something like straight urea or milo i don't think i would be as concerned. With the P and K element fairly strong in the starter - i would want that to have time to work its way into the system.

Pretty much what BoatDrinks said. Milo, urea, or a high nitrogen (low everything else) fertilizer is not an issue. Some labs don't test nitrogen. Any good soil review will ignore your nitrogen or specifically mention it doesn't matter a jot (it varies too much due to weather conditions, time of day, and so on).

For starter, 3 weeks with normal rainfall or irrigation is about the right time to wait.

You could go earlier, but when quoting your test make very, very sure to mention that. Several times. Underlined.

Thanks for the response everyone. I've watered twice about 3/4" each time and it has rained pretty hard a few times. I think I'm outside the 3 week window you've recommended.