I was a skier long before I switched to a splitboard, but I usually test out any changes to my setup at A-basin before doing longer tours in the BC. Since many times early on I was testing out both touring and riding - I would just skin up, even though I had a pass to ride the chair. A-bay is usually really cool about that so long as you stay to the side. Just make sure your skis have brakes or a leash if inbounds. I would certainly wait until a vast majority of runs are open - don't poach trails that aren't open or skin up the 'white ribbon of death'
In essence though, what I am saying is; splitboarding isn't exactly a dialed in science so often times I used the resort to test things out.
My roomate is a solid skier and we usually end up in the BC on the same hut trips and day trips together. She upgraded her sticks this year to the Black Diamond Starlets and I think she plans on a few days inbounds to dial them in - especially where she wants her DIN number to be. Since her Starlets are rockered, I imagine the numbers will change. Granted, inbounds she has a very aggressive mogul style, but not exactly the case in the BC as she exercises more caution on the terrain. Again though, she doesn't want to mess around dialing in her bindings in the BC or experimenting with lateral release adjustments.
It is different for everyone, but her system of transitioning form inbounds to the backcountry worked very well; taking a level one avy, and getting all her avy gear (and practicing with it) her first year, and doing rather side country stuff at Loveland Pass and full moon descents numerous times. When she wanted to ski aggressive terrain she would put on her downhill skis and head to A-basin. The second season she dropped the coin on Scarpa Gea's, and Dynafits. She opted to buy cheap skis and skins her second season [last year] in the BC. Again though, this season she has come full circle and upgraded her sticks now that she knows her skiing style in the BC - which is totally different that what she does at resorts. Everyone is different, but I suppose this was a good system for those that like to enter the pool gradually
As nkan mentioned with boots - keep in mind that an AT boot is made from a different plastic than its inbounds counterpart that stays more flexible to lower temps. If you are tearing your AT boots up inbounds with the same skiing style as in the BC - you may want to look at a more rigor AT boot. I know numerous people that ski with Maestrales inbounds to include many ski patrol for the obvious benefits. These however are a four buckle boot and are designed for aggressive skiing, yet have the ability to travel on foot easier being an AT boot. In my experience when skiing in the backcountry, you are at times on some of the worst skiing conditions you could ever imagine - bullet-proof crust, ice, sluff pockets, scarp, bottomless powder - often all at the same time. There is nothing at a resort that could come close to that abuse on equipment - IMO.