Source : Webster's Revised Unabridged Dictionary (1913)

Initially \In*i"tial*ly\, adv.
   In an initial or incipient manner or degree; at the
   beginning. --Barrow.

Source : WordNet®

initially
     adv : at the beginning; "at first he didn't notice anything
           strange" [syn: {ab initio}, {at first}, {at the start}]