Like I said in Q is a fake ability decent players just won't eat a random bubble, so you want to set it up with R first, which is, as the LCK caster said, "phat".

When getting dove - he ults as wukong dashes in on him and since wukong is right on top of him he follows with bubble pretty much immediately after

When chasing - nami ult is slow so it helps sona/wukong are next to a wall, and have less of an angle to sidestep. Nami E/mandate on azir right before also set it up with a slow and damage. Wukong and sona don't flash the r/q and die.

Hitting bubble when chasing or getting dove by mobile and slippery champs like wukong is not possible whereas ulting like this first gets at least a flash.

Tangentially, the sona pick was interesting this game, they 2v2 killed lvl 2 but it was more the lucian lvl 2 powerspike vs zeri than sona vs nami I think, although sona lucian is a real lane. But pro sonas get no gold from fights and spend their meager allowance on pinks so it takes forever to get a mythic and they just never get a second item, so they don't really scale that well. Also maybe in a baron fight sona had an opportunity to chain cc gragas with wukong r->sona r->jax stun but didn't use it instantly and gragas flashed out (maybe he had tenacity or something and would live but idk early sona ult on whoever is in range for you/your team to is often good).