I’m confused now...so you can get the gate check tag at the normal check-in point? And then just hand it to them at the gate?
I’d be checking one bag the normal way...my suitcase. But I’d want to gate check the guitar.
If you tell them at the main gate that you want to carry on the guitar, I’m sure they’ll tell you what you need to do at that point. Don’t know if they’d give you a tag at that point, but just ask them, they’ll tell you. If you give yourself an extra 20-30 minutes, you’ll be just fine, because you’ll have plenty of time to get your questions answered.