Currently as
@Zixi1000 says it's 2 bags a month but only one can be a classic. At least with the boutiques I shop at you can't purchase 2 classics in the same month. I just ran into this today. I recently purchased a navy CF that my SA has had me on a list for and I didn't realize it was rung up on 10/1 and not 9/30. I inquired about a grey CF today and was told I couldn't purchase under my profile because I already have a classic purchase for Oct. I was bummed but I heard a sigh of relief from the my DH LOL.
Edited to include: My SA also told me about the reserve limit because too many people were getting on multiple lists for multiple items. She said they (Chanel) wants to make it fair and ensure that everyone that wants to purchase has an opportunity to do so.