Hi,
As a standard you should likely 3bet that preflop BBvsCO, tho if you know what you're doing postflop and villain folds to 3bets a lot preflop, flatting planning to c/r a lot of boards is an okay option.
Once he 3bets the flop small i don't think he intends on folding anything, shoving is fine to stack all kinds of draws and worse made hands out there.
Hope it helps.