It has been a while since I worked on site, I am now in a vendor role, but I can say from experience, the less complicated the better. I understand the reasoning behind structuring the bonuses based on increasing revenue, but if you make it too complicated, its more work for you in the end and the leasing team gets frustrated with a complicated system.
I would do a separate bonus structure for the Manager, as they should be evaluated on NOI, since they are repsonsible for the overall performance of the site. Looking at Quarterly numbers would be best for the manager as budgets can be hard to follow month over month, depending on how expenses hit, but looking at the NOI after 3 months should be a fair assessment.
Assistant Managers should be evaluated on new leases, renewals and delinquency. (assuming they do participate in leasing and renewing) For the delinquency, I would set a specific amount tied to a percentage of delinquency. i.e. $250 for delinquency under 1%. $200 for delinquency between 1% - 2% etc.
Leasing agents should be evaluated on new leases and renewals. Having bonuses based on lease term would be ok, but I would limit it to something like 6 - 11 month leases get $25 and 12 + get $40
I don't think leasing people should have the ability to structure concessions because it can lead to fair housing issues. Concessions and prices should be set by the manager or above. As long as they ensure that the lease paperwork is completed accurately and they follow the pricing and concession guidelines, they get paid their bonus. Failure to comply means no bonus for that lease. The leases must be in order to count if the property is sold, so it is important that they complete the paperwork correctly. Scrambling to fix things during the sale or audit process is too late.