Erst \Erst\ ([~e]rst), adv. [Orig. superlative of ere; AS. [=ae]rest. See Ere.]

[Archaic]

1. First. --Chaucer.

2. Previously; before; formerly; heretofore. --Chaucer.

Tityrus, with whose style he had erst disclaimed all ambition to match his pastoral pipe. --A. W. Ward.

At erst, at first; at the beginning.

Now at erst, at this present time. --Chaucer.

Source: Webster's Revised Unabridged Dictionary (1913)