Firstly in a sentence as an adverb

As a female math grad and CS postgrad, I would like to say firstly that you have successfully trolled me.

My counter was "firstly, the point of 'social security' is to keep people socially secure, at least for short stints, which means not kicking them out of their homes for a handful of dollars".

Firstly definitions

adverb

before anything else; "first we must consider the garter snake"

See also: first foremost