Priya,
Its about ten patch levels . If your basis person can start the download immediately , he will need approximately about 8 hours to get the changes into the dev. system .But in this case basis team will have to check for dependent patches of other modules as well.
Development server takes a little longer .If you can finish by tomorrow morning , testing can be done in a couple of hours .Because a patch upgrade does not change any old functionality , it adds new features.
QA system should be faster. If all goes well , the pay can be run on 31 st in the production server .
Whatever I have written is only an information , may be not the approximate estimate of numbers.
You can only get the correct analysis from your basis team.
Regards
sandhya