Probably asked before but...

[Trig]

We've seen it on many episodes before, that when a gate is being dialed, the destination gate starts to spin before the wormhole is established..
But how does the target gate know its being dialed before the big red button in the middle of the DHD is pressed?

Or is it just one of those 'whoopsie' moments?
For instance, and because I'm up to ep9 on the SGU rewatch, the gate on Destiny starts to spin before the gate is actually active and the ship drops out of FTL....

[StargateMillennium]

I think it's a whoopsie moment. Stargate has quite a few of those regarding the stargate. In one ep, Walter gets SG-1's IDC before a wormhole is even established.

The only other possibility I can think of is that even though we're witnessing the events side by side, the destination gate is actually activating post the activation of the origin gate but that's just a headcanon concept.

[Trig]

So in that case, if you dial a gate and jump straight through you get buffered for a while until the target gate has done its dialing and opens, bufferings bad lol..

Also, on another gate question, when Baal messed with the code of the gates and dialled multiple gates all at once, what would happen if you jumped into a gate then..

[Rohan]

I don't think it's a whoopsie.

If anything, I kind of think of it as old fashion internet dial up when two gates are connecting. When the destination is inputted into the gate I surmise it's communicating/signaling with the connecting gate as they both start to spin to establish the connection. Not only to create a safe connection but also to give folks on the other side time to see that something is coming through and best to get clear.