depends on situation but: NEVER before reaching a nice slow taxi speed. NEVER in a high workload situation.
Various scenarios:
In low visibility it may be advisable to clean up quickly even on the runway once the captain has control in order to have acomplished these tasks before looking out for the correct taxi turn-off.
In the same low visibility scenario it may also be highly advisable NOT to clean up because you need all eyes on the runway to find the taxi turn-off lights and identify the intersection your about to leave. Then call vacated, change freq. and call ground. you still have time to clean up once on a straight piece of taxiing.
If your taxi turn-off is far away, clean it up.
I don't think that the gear problem is an issue here. The lever is usually far from anything you would touch during the cleanup.
Extremely busy airport? You may wait for a straight strecht of taxiing for clean-up and after landing check.
The message?! Clean up when the boss tells you. If it is left to your own judgment: clean up when you feel like and your eyes are not needed. (Just try to clean up before entering the stand
it is not very elegant to park with everything still hanging out and maybe even the strobes still blinding everyone.)