I entered the wrong date for the date of me being employed for a job, is this a serious matter?

[CarolynM]

Not unless you claimed a deduction which is triggered by employment and the wrong date is significantly inaccurate. 

For example, moving expenses are deductible if you moved for a job, but you must start the new employment near in time to the move.

Otherwise, it is considered a typo that can be corrected later.