It took about 5 days for me to sync the blockchain. That wasn't constant online time, but elapsed time. I just logged in when I felt like it, and let it run for a while. The more I read about 3rd party wallets, the more I realise that I did the right thing in loading Bitcoin core.
Make sure you encrypt your wallet (password protect it) & you're about as safe as you can possibly be.
Make regular back ups too, I 100% swear by Bitcoin Core.