The Collaborative International Dictionary of English v.0.48:

Betime \Be*time"\, Betimes \Be*times"\, adv. [Pref. be- (for by)
   + time; that is, by the proper time. The -s is an adverbial
   ending.]
   1. In good season or time; before it is late; seasonably;
      early.
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            To measure life learn thou betimes.   --Milton.
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            To rise betimes is often harder than to do all the
            day's work.                           --Barrow.
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   2. In a short time; soon; speedily; forth with.
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            He tires betimes that spurs too fast betimes.
                                                  --Shak.
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