This depends on how the plan is written.
Most plans with which I've worked required that the annual contribution be paid in 'substantially equal' monthly deferrals, although I have heard of 401(k) plans that allow accelerated contributions for those who wish to make most of their annual contributions early rather than later in the year.

Are you wishing to accelerate contributions to maximize employer matching? If so, this probably won't work, as employer matching is usually made on a monthly, quarterly or even annual basis...and if this is not a safe harbor plan, the plan could use the 'last day' rule, which means you would not get the employer's match unless you are employed on the last day of the year....although the plan may make an exception for those who are (per the plan's definition), retiring.

Check with your plan administrator or read through the plan's Summary Plan Description.

BruceM