Depends on the version of Kickstart. For 3.1 it's around 30 seconds. For 3.0 it's a bit less than that. There's nothing you need to do. If the screen is any colour other than black during this delay, then something is wrong. If it stays black, then something is wrong. If it pauses for around 30 seconds on the black screen then shows the Kickstart screen, then this is fine.
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moto