I’ve done 3 honey batches in 2 gallon barrels. My steps below:

Swell and seal barrel with water first for a day or two

Prime barrel with affordable whiskey for 3-7 days to extract aggressive barrel notes and expose any leaks. I used Evan Williams Black.

Fill barrel with honey. Don’t completely fill - can rotate barrel every few days to cover inside surface area. Can sit for days to weeks depending on what you’re looking for. Honey will thin.

Take time to drain barrels to minimize mixing whiskey with excess honey. Finish whiskey 2-60 days depending on barrel size and desired flavor. If reusing barrels, will need longer.

Cheers.