Can I change the ownership percentages for a S-Corp in the middle of a tax year?

This year, I filed form 2553 so that beginning with tax year 2017, my LLC will be taxed as a S-Corp with the IRS.  On the form, I put the ownership percentages as me the sole owner.  However, since then, another member has joined as a co-owner. 

We want to take profit distributions (i.e. owner's draws) this year, which are not subject to payroll taxes, but since he is not currently listed as an owner with the IRS, I don't think we can do that.  Is there a way we can still do so?