I typically reserve some amount (bigger than I have) before closing wallet (Settings->Options->Main->Reserve). Then when I open it again, I let it sync, then remove the reserve and let it stake. Then again reserve before closing.
That way it doesn't try to stake when opened again (before you manually allow it), so it can sync without additional hassle

Its a bit more work every time to remove reserve, then set it again, but it ensures less issues with sync.
I haven't tried it with OMC yet but a lot of coins allow you to put reservebalance=999999999, or other amount, in the conf file. That would save at least the trouble of manually reserving it prior to closing the wallet.