What is the Earliest Source? 4 - Saying Aqdamut before Laining

Originally Aqdamut was recited AFTER laining the first passuq of the Shavuot morning laining. This tradtion has been preserved in the Roedelheim Machzor

However, in most Machzorim that have Aqdamut, it's been moved to just before the laining.

What is the earliest source suggesting relocating Aqdamut?

KT
RRW