Those "who know" leasing on this forum have in the past advised to not dicker over monthly payment. But I don't know what the practical difference is: if you only go in with a maximum price out the door, and monthly payment isn't an object for discussion, how does leasing make sense in the first place? I know: Kia incentives on the Stinger. That is the game changer: with leasing rebates sometimes in the $9K range (!?) it makes sense to get as much of that as possible and then do the buyout.
But typically, normally, leasing is for people who can't afford the higher monthly payments of financing to buy. Leasing allows lower monthly payments. So dickering over a maximum monthly payment (as you did) seems logical to me if you are not going to exercise the buyout. If you expect both a lower monthly payment and then do the buyout, why bother fighting for a lower monthly payment?
Lower monthly payment results in less of the Kia lease rebate/incentive applying. The dealer will tack on added costs and fees to reap a profit, gouging the incentive to nothing (It looks like the OP's incentive exactly equals the amount of the first payment). But if you go for a higher monthly payment and lower out the door price, then the incentive will apply more to get to the lower agreed price, and then you do the buyout and reap the reward of a lower out the door price.
(I am inviting correction/education on this: because leasing was entirely new to me a year ago, and I have slowly pounded what I think I understand about it into my middle aged brain. No doubt this is yet one more area where I know far less than there is to know.)