That is strange that they are appraoching with the wind as waterfowl usually will always land into the wind if there is a wind as it makes for an easier landing for them. Good to hear that you have decoys in the water as the water/field set up can be very deadly. Are you keeping the decoys out all the time? Reason I ask, is I have bit of reservation of them getting used to the decoys. Remmeber decoys purpose is to lure them into within shooting range, and if the lure is gone because of they are accustomed to them, the attraction is then gone.
Remember Snows are not at all like Honkers or Specks that will readily commit. If you can break off a family group to come in at 35 yds--let 'em have it. Granted at times they will comes in like Honkers with feet stretched out and landing, but the vast majority of the time they won't. Also if circling at say 40 yds and it is the 2nd swing, odds are they will not be coming in closer. It seems more times the 3rd or 4th pass they are out further. So that 2nd swing they is not coming any closer, so shoot at 1st or by 2nd passby in my experience, or if out of range, that is hunting and maybe another flock with be different result. That is why they call is hunting VS shooting. :mrgreen:
Lastly, as too how far. Hmmmm. Well I suggest looking at the topics in the Shooting forum. A couple are very pertinent to this. I am real good short range (to 40yds) and a better than average long range shooter, and I will shoot to 65yds, but I have loads and chokes that ballistically can kill that far, and the confidence (experince) in my shooting abilty to shoot that far. But most guys are poor shooters past 40 yds. So the question One needs to ask One self is 3 fold when pass shooting (+40yds): Do I have the right loads? the right chokes? (meaning have had done patterning, etc.) And the personal shooting ability to shoot at higher birds? All 3 must be a yes answer. Basically know your personal limits.
Oh BTW, are the decoys a mix of Snows/Blues matching the ratios of the flocks there? As guys with Snows only in the MS flyway will not do as well as those using mixed. (geese are sliding off way more often with Snows only spreads) I personally use at least 50% blues now.
I hope I was of some help. And hopefully a few other experienced members here will also post up about their experiences too.