It's not RegEx at all. It's a Word wildcard Find/Replace. Although there are some similarities, they are not the same.

For what you want, try a Word wildcard Find/Replace with:
Find = ([!^13]@) ([0-9]{1;2} [jfmasond][a-eéilm-prt-v]{2;8} [0-9]{4}.) (*^13)
Replace = \1^t\2^t\3
This assumes the months will all have valid characters. If not, try:
Find = ([!^13]@) ([0-9]{1;2} [jfmasond][! ]{2;8} [0-9]{4}.) (*^13)
Replace = \1^t\2^t\3

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]