Notice the thrice repeated before, emphasizing the injunction to have everything ready before Paul's arrival.
Make up beforehand (προκαταρτίσωσιν)
Adjust. See on Mat 4:21; see on Mat 21:16; see on Luk 6:40; see on 1Pe 5:10.
Lit., blessing. In this sense only here in the New Testament. In the Septuagint indifferently of gift or blessing. See Gen 33:11; Jdg 1:15; Eze 34:26. In Pro 11:25, liberal soul is rendered by Sept., εὐλογούμενη blessed.
Whereof ye had notice before (προεπηγγελημένην)
Rev., better, your afore-promised bounty. The bounty promised by you, or by me on your behalf.