at erst

from The Collaborative International Dictionary of English v.0.48

Erst \Erst\ ([~e]rst), adv. [Orig. superlative of ere; AS.
   [=ae]rest. See {Ere}.] [Archaic]
   1. First. --Chaucer.
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   2. Previously; before; formerly; heretofore. --Chaucer.
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            Tityrus, with whose style he had erst disclaimed all
            ambition to match his pastoral pipe.  --A. W. Ward.
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   {At erst}, at first; at the beginning.

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