What is the maximum amount of cc advised to put in each bum cheek on first BBL?

When discussing BBL, there are no absolutes. The maximum is ultimately a reflection of the available fat donor sites. There are limits on the amount of fat which can be safely harvested in an office OR setting (no such limits exist in the hospital). This limit is typically quoted as 5 liters (however, there may be state to state variation). Additionally, there is a limit to the capacity of the recipient site as the buttocks can only hold so much volume.
With regards to your specific question, the goal is to reshape the frame and fill the deficient areas. I generally consider 500 cc per cheek to be a minimum assuming for moderate resorption. Keeping in mind the limits for lipoaspirate, the determinant of available fat is the ultimately the patient and the capacity of the recipient site. This means you must have goals which align with both the fat you have available for transfer as well as what volume one can reasonably expect the buttock to accept.
As always, discuss your concerns with a board certified plastic surgeon (ABPS).

There is no set "maximum" amount. The amount that can be injected into each buttock cheek depends on the amount of stretch or volume that can occur. It will be different for each person and based on various factors - skin elasticity, buttocks dimensions, etc. In my practice, the minimum I inject per side is 500 cc. Less than that doesn't seem to garner a significant change. There are exceptions for those who just don't have enough fat to harvest, but these patients also have realistic expectations of what less than 500 cc will do. Too much fat injected into the buttocks may lead to seromas, large lumps and nodules, and a disproportionate and unsightly appearance. More than 1000 cc per side can start leading to more complications. There are indeed plastic surgeons who inject very large volumes into each buttock, but these surgeons rarely show LONG-TERM results! They only show how it looks immediately after surgery when the patient is still in the operation room. That is false advertising and is misleading. It does not give you a true representation of what the buttocks will look like long-term after swelling has gone down and sitting has resumed. Tip: If you see these types of photos (immmediate postoperative photos) displayed by a plastic surgeon as examples of his BBL results, run far and run fast. Best of luck.