Flavored caramelization When should flavorings to brown sugar-caramel be added: during caramelization of after?

I make caramel regularly for inclusion in coffee based drinks. The caramel recipe is simply: brown sugar caramelization via heating with water (up to 260 F on a candy thermometer), then the addition of honey (invert sugar) and a butter vanilla oil/flavoring.

I haven't gotten around to testing, but I wonder if there's any knowledge on whether flavorings like butter vanilla assimilate into the total flavor better if added during or after caramelization?

Or the chemicals of the flavoring don't integrate with the chaining of sugar molecules so it doesn't matter? The butter vanilla liquid I'm using seems to be a polar substance since it mixes well with water.
Most of the aromatic compounds contained in vanilla are highly volatile and / or degrade in high heat, so I would add the vanilla after caramelization.