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It depends on which moon(s). Io moves the fastest, followed by Europa then Ganymede then Callisto (with respect to our viewing position).
Io moves faster than the rotational speed of Jupiter, so you really need to capture for a less time otherwise you can end up with a blurred or elongated moon.
The length of capture really depends on your focal length. For short focal lengths, say under 4500mm or so, there wouldn't be much rotation shown in over 3 or 4 minutes. At 9500mm FL, I capture for about 2:30 (45 seconds in each channel) and that's about the limit I can go, and even then there can be a 1 or 2 pixel shift required to align the red channel (captured first) with the blue channel (captured last).
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