rober, I did a drizzle this afternoon on newly installed bee packages. Some well respected local beekeepers talked about doing this before our local bee club. There were finding mites in packages and this got them off to a great start. I also found this article by Randy Oliver.
http://scientificbeekeeping.com/oxalic-dribble-tips/ This is a section I found particularly interested.
"Alternatively, although you could directly treat bees in a package, I’d suggest installing them normally, and then treating them in the hive between Days 5 and 7 after installation. The timing is due to the fact that even if the queen starts laying eggs the day after installation, it wouldn’t be until Day 9 that the first brood would be of suitable age for mite invasion. Oxalic dribble kills mites for roughly 3 days after application. Thus, if you dribble the recently-installed package on Day 6, the full effect of the treatment will have taken place prior to the first opportunity for the mites to hide in the brood.
You can also use this method with shook swarms, or for any divide made without brood."
This happens to be DAY 8 since installing the packages. There was no sealed brood. So I was still within the acceptable time frame.