As regarding the timeframe of Latin ae>e Rosetti indicates that
Varro talked about e for ae (in the countryside) indicating hedus
against haedus.
Varro => 116 BC-27? BC see at
http://evansexperientialism.freewebspace.com/varronis_latin.htm
So we can supposed that Latin ae > e became general (= finished) in
sec I CE
Best Regards,
Marius