Retirement tax questions

@ChampChiranand anybody else who wants to chime in.

I have gotten here by the rabbit hole.

My 2017 box 2a states unknown. So that means the Simplified method for a 12 month time frame. I even created a spread sheet for the next two years.

But my 2016 OPM 1099-r states the starting date of 06/01/2016. The box 2a has an amount in it. So I assumed the Simplified method starts in 2017 with no previous year recovery amount (0) for line 6.

But my concern is the later 6 months of 2016. If the box 2a has an amount am I to assume that 2016 is not included in the Simplified method worksheet and that box2a taxable amount is already correct?

I assume that the blank amount in box2a triggered the Simplified Method in TurboTax?

I hope I made this clear. I could have started a new question but it ties in here so clearly.

Thank you in advance.

I would really like to finish up at a decent hour. 8-)