When I typed in "dumpwallet" where does the file save to? or how do I see the information you are talking about?
for example on console you can type:
dumpwallet privkeys.txt
and the output file privkeys.txt will be saved in the same directory of your wallet.dat
then just open the text file normally,
in each line, after private key it shows the date when that specific address was created
though I'm not sure whether the date info is accurate for older wallet like yours