Hi Ranochigo,
Thank you for sharing.
My Bitcoin Core wallet is showing blockchain as of December 2016, and there are more than 3 years of data to download for around 3 weeks. That's a very long time to wait for a full sync.
I can see the current balance is exactly the same as I had before, because my last balance was in 2015 without making any transactions since that time.
May I ask you, if I send some BTC from Bitcoin Core to Electrum now, will the transaction be completed within an hour or will I have to wait for the full sync of 3 weeks for the transaction to be completed please?
Thank you a lot.
Best, T.
As long as the UTXOs from the transactions are unspent, your client can craft and sign a valid transaction before broadcasting it.
If you don't wait for it to fully synchronize, you might miss a few possible transactions that were sent more recently. Having it fully synchronized is the only way for you to be sure that you're not accidentally crafting any invalid transactions.