premillennially

pre·mil·len·ni·al

 (prē′mĭ-lĕn′ē-əl)
adj.
Of or happening in the time before the millennium.

pre′mil·len′ni·al·ly adv.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

premillennially

(ˌpriːmɪˈlɛnɪəlɪ)
adv
from a premillennial point of view
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014