As @mllcb42 would say, do your research before you approach any dealer.
First, find out what the BMW current numbers (money factor, residual value, and lease cash/loyalty (if you qualify) or other incentives are for this month (these numbers vary monthly). You can get some information on how to do so here. tl;dr = go to edmunds forums and ask
Second, research a reasonable pre-incentive discount (pre-incentive meaning before lease cash, loyalty, and any other rebate from BMW) based on other posts here, or what brokers are offering. For BMWs generally, new cars from dealers are getting discounted anywhere from 10-11% before rebates. Here is a post on a deal on a new X1 recently. Search “bmw x1” in the search bar above, sort by most recent, and go through the first 15-20 entries, that should give you a good idea.
Third, use the LH calculator to figure out what a reasonable monthly payment would be, plugging in the data you got from steps 1 and 2 above. @mllcb42 has a nice post on how to use the calculator here. Figure out if you want to put down multiple security deposits (MSDs) to help bring down the money factor on the BMW if you want (more here on that).
After you did all the above, construct the deal you want. You should have a reasonable monthly lease number in mind based on the calculator work in step 3 above. @michael has given you the right language here, I think it’s right to use that. In my case, I wanted to specify the exact money down (so no surprises) and MSD amount (7xMSDs = $3500 for example). But then I went dealer to dealer, and just used the same language and see who would play ball.
Good luck!