The 1841 British edition accidentally dropped the word even from this passage. The subsequent 1849 LDS edition restored it. The word even is similarly used in the very next verse: “even down to this present time” (Mosiah 1:4). King Benjamin also uses the expression “even at this time” three times in his final discourse to the people (but without the word present):
Thus the use of even in Mosiah 1:3 is quite appropriate.
Summary: Maintain in Mosiah 1:3 the use of even in the phrase “even at this present time”.