Found old Bitcoin wallet of mine, but has unconfirmed transactions from 2013
If they are outgoing transactions they will always appear regardless of how far behind the synchronization is. Any unconfirmed transactions will have long bounced back to your wallet by now. Try going on the command prompt (.cmd) on your computer and type in:

"C:\Program Files (x86)\Bitcoin\bitcoin-qt" --zapwallettxes=1

Or try:

"C:\Program Files\Bitcoin\bitcoin-qt" --zapwallettxes=1

Your bitcoin core wallet will re-scan and the bitcoins will show up on your wallet.

If they are incoming transactions that you are waiting for you will just have to leave the bitcoin core wallet open until it synchronizes to the date the bitcoins were received. This will probably take a few days.

Hope this helps...

James