Instead of adding Con I think for long term balance it is easier to just get your Level 2 or 3 hit points at Level 1 then not get HP for those levels.
2nd: d10=16+2xCon, d8=13+2xCon, d6=10+2xCon.
3rd: d10=22+3xCon, d8=18+3xCon, d6=14+3xCon.
If they multiclass early then adjust.
I'd also adjust gear so not every low level goblin with no treasure at all, isn't running around optimised with well crafted gear (70gp).
Clubs (d6), shanks (finesse, d3), primitive bows (d4), sharp sticks (d4), rocks (1), crude machetes (d6).
I'd mix up the Redbrand gear as well (65gp).
But that's more of a world-building thing.
That is a great suggestion.