I still have probably over half a year until mine gets approved, but i'm just wondering how you all knew when yours was approved?
I tried looking this up, but the only thing I saw was saying that you can call the ATF to get a status update on your form.

Your dealer usually contacts you when they get the stamp in.

All you can do is call (304) 616-4500 and ask. Ask to check on your form 4 transfer, give them your NFA item's serial number, who it is coming from, and who it is going to.  They will tell you one of three things, unless you have an error.
It's not in the system yet.
It's pending as of xx/xx/xx.
It was approved on xx/xx/xx.

Or you can just wait to get called by your local sot when it's ready to be picked up.

Yeah, don't wait for the SOT to call you, verify they actually submitted it.

And it is just Wonderful when you call and they tell you the form wasn't submitted/they have no record of it ... I guess it will be 4 yrs before I get those cans...

Out of spite I may just buy another set. Through a different dealer.