First AA ( Alcoholics Anonymous ) does not formally say anything about chips or medallions or the milestones for which they are given. AA does not have in their program or official texts any guidance on medallions or the giving of chips. Instead you could consider this a cultural "norm" that each group or members decide for themselves. Some groups do not give chips at all. Some of them give coins for 1 3 6 9 then 1 Year and then 18 Month and then each year after starting with 2 years. Some groups may give medallions for each month there are sets of AA Chips you can buy for Month 1 - 11 and those come in either Aluminum or Bronze. You can even buy fancy versions of these month sets.
Some groups have added 2 Month to their mix and as I mentioned earlier, AA takes no stand on this its a decision that the group conscience must make.
There is another coin that is given out called a 24 Hours or Desire Chip. Sometimes its just a plastic chip or sometimes its an aluminum or bronze 24 hours chip.
So there isn't a good answer to the question regarding the AA Milestones you would have to visit a group and see what norms they have adopted if any. That said if you are purchasing a coin you will find them in 24 Hours and Months 1 2 3 4 5 6 7 8 9 10 11 and 18 and then Years 1 - 65
If you would like to see some of the Month options available take a look at our selection of AA Month Coins.