Adding a sand bed at a later time.....

[FitoPharmer]

If it is new sand from a bag I wouldn't bother adding it a little bit at a time or cycling it before adding it. If your bottom is covered in life I would give it a good brush, scrape, vac before adding the sand, maybe with your next water change? Anything left after that is most likely less then a over feeding or two, that your tank would handle right? If you rinse your sand well, choose a proper grain size for your water movement and needs, and add it carefully. There is only one sand storm that you have to clean up.