Too late for you now, but for the last several years of employment I front loaded the entire years 401k contribution into the first few months of the year. The employer plan allowed up to 80% of pay contributions, so I set January's contribution to as close to 80% as possible and still have $ in the paycheck to cover the health insurance, etc deductions.
That way if I got laid off mid-year (as eventually happened) I would still have the full years contribution and a lot lower taxable income for that year.
The year I did get laid off (may 31), I flexed the start of taxable unemployment compensation to start in December so that the bulk of it (capped by state law at a whopping $240/week) showed up on the following years much lower tax rate.