Bills do not always bring rookies along slowly. They have started rookies in past. It depends on what system they went to college, their skillset and how well they do in camp.
Cornerback Christian Benford in Round 6 of the 2022 NFL Draft started vs Rams in opener.
https://nflcdns.nfl.com/liveupdate/gamecenter/58838/LA_Gamebook.pdf
McKenzie is better as 3rd WR as opposed to slot receiver.