Exactly as @pvc says. Once your Bluetooth is turned off in your phone, the Omnias don’t even know your phone exists!
But once SmartFit has identified your hearing aids, you have to restart them again before SmartFit will connect. This is a security device, so you don’t inadvertently connect to the wrong pair of hearing aids.
So you have to restart them twice possibly. The important time is between SmartFit finding them and SmartFit connecting to them. I speak as a SmartFit user myself, rather than as an expert.
Incidentally Resound have recently released SmartFit 1.15 update 2, are you using that?