I did a post touching what your talking about. It has the earliest references I could find to Matt 24:36, Mark 13:32, Acts 1:7, in Patristic writers.
It may or may not be of use.
Origen in his Commentary On Matthew 55, has a big section on Matt 24:36. I haven't been able to find an English translation of the text. I think it would make an interesting read.
Big hat tip to Matt13. This information is very useful. Please check out his blog.