From ripe +‎ -ly.

ripely (comparative more ripely, superlative most ripely)

1. In a ripe way.
2. maturely; at the suitable time
   • 1611 April (first recorded performance), William Shakespeare, “The Tragedie of Cymbeline”, in Mr. William Shakespeares Comedies, Histories, & Tragedies[…] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act III, (please specify the scene number in lowercase Roman numerals)]:

     It fits us therefore ripely / Our chariots and our horsemen be in readiness:

• Ripley