Hi there, David!
In the afternoon/evening, Resort buses will generally stop at
Typhoon Lagoon prior to heading across the street to
Downtown Disney, home of
Cirque du Soleil. You will want to confirm with the driver that the bus is bound for Downtown Disney prior to its Resort loop route.
You will definitely want to leave time to wait for the bus. While the journey across the street isn't long - 15 or 20 minutes, perhaps - the wait between buses can be long, depending on the crowd levels, the number of buses running, etc.
Because I tend to err on the side of caution, I would plan to arrive at the Typhoon Lagoon bus stop at least 90 minutes in advance of when you want to be at Cirque du Soleil (which is likely before the performance). That might seem extreme for a reasonably brief trip, but you'll want to build in wait time, drive time, and walking time from the bus stop to the Cirque du Soleil venue.
And don't worry if you arrive well in advance of showtime. You're surrounded by all kinds of shopping and dining in the Downtown Disney entertainment district.
Have a wonderful time!
See you later, celebrator,
-Deborah B.