Hard to tell from the angle on the one picture of the bottle, but it looks to me like that lip is going to be somewhere in the 1790-1810 range on the illustration of lip forms. If that illustration is definitive, it's an earlier bottle than 1820. Nice!
Based on coins we found with similar bottles in Charleston, SC I would guess 1820 +/- 10 years. We found Spanish coins dating back to the 1780's and US coins from the first and second decade of the 1800's. Nice piece, I would have left the oysters on it.