I woud put everything into the pool. Its too late for 2016, but put all 2017 and 2018 into the pool, and next January put the 2019 into the pool

so given that 166k contract and assuming you use 190k this year, you will go into 2017 with 474000 points in the pool

use 190 in 2017 and pool the 2020 points in Jan 2018 and you go into 2108 with 450k points

and so on and so on

assuming 166 new points each year and using 190 each year you can take 6 or 7 years to decide whether to buy more and how many more to buy.

using the pool like this will cost you $39/year. You could (as you suggest) just borrow what you need from the next year, and it wont cost anything extra

It sounds like you have done a good job figuring out how many points you need.. instead of buying that Bonnet Creek contract, why not biy something at the 190 mark, or even better 231000. Thats an even multiple of 77000 and you get one reservation transaction per each 77k, and 231 is right at the point where you dont get zinged for the minimum program fee. And if you can buy what you want in one contract the closing costs and transfer fees will be cheaper than doing two purchases.

Thats my advice, buy what you need now in one transaction instead of piecing it together over time.