The coins are still there. I guess I can try some dates
I would start with
2009-01-09 (Bitcoin's first transaction date)
2016-05-05 (the date that wallet got funded at)
Make sure you do tests offline, or if you are knowledgeable enough, on a live OS, still offline. Hacks are really a thing and 10
BTC is an overly good looking amount.
Make sure you know how your father was writing the dates (mm/dd/yyyy. dd.mm.yyyy, yyyy-mm-dd or other ways)
Beware of people that may offer you help in private, some may be scammers.
Good luck.