When I'm on my home network, it's almost the same time, or so close together it makes no difference. When away from the network, that is, when the syncing is through Bluetooth, it can take longer. I haven't timed it, but 30 seconds or so seems about right.
Sometimes, I don't even get notifications. I don't think the BT link is very good. I left my phone in my pocket all day and I only received about 25% of the notifications on my watch. My phone buzzed like crazy all day, but only every once in a while did my watch notify me. I have all of the notifications set to mirror my phone. Sometimes they do; most of the time they don't!
While my watch is unlocked i don't receive notifications on my phone. They all go to my watch. if im using my phone at the time of a notification comes in then i recieve it on my phone and not my watch.