Green’s Dictionary of Slang

excellently.

1755		Johnson Dict. Eng. Lang. (1785) n.p.: Primely [...] 2. Excellently, supremely well. A low sense.
1830		Lytton Paul Clifford III 244: Harry spoke up for you, and said as ’ow though you had just gone on the town, you was already prime up to gammon.
1848		J.R. Lowell Biglow Papers (1880) 48: Warn’t we gettin’ on prime with our hot an’ cold blowin’, / Acondemnin’ the war wilst we kep’ it agoin’?
1857		Dickens Little Dorrit (1967) 109: ‘Is it very pleasant to be there, Bob?’ ‘Prime,’ said the turnkey.
1873		A.G. Murdoch Lilts on Doric Lyre 26: He who this night dares the road, Should have his good steed primely shod .
1885		‘’Arry on ’onesty’ in Punch 31 Jan. 60/1: ’Ow are yer, old hoyster? For me, I’m a gitting on prime.
1900		A. Lang in Blackwood’s Mag. Mar. 367/1: It was primely witty to half-poison somebody with a surreptitious dose of medicine .