I wear a 7mm farmer john - with a 3mm dive jacket - under that is a sweatshirt - sweatshirt gets saturated and body warms that water =eventually = got to bear the initial chill for a little while - unless you bring a jug of warm water to pour into suit
I usually get tired before I get cold - can usually last about 3 hrs - if Im digging
7mm gloves - 7mm dive boots - with thermal socks underneath those
taken some yrs to get things the way I like - have other suit configurations that I have tried and use too