[weaksauce]

Managing expectations is so important and you really should learn it early on in your career. If you pad your expectation and then deliver it early you delight. On time and you are still ahead of most freelancers/employees.

If you see problems ahead with the timeline, communicate and let them plan around your delays otherwise you are surprising them in the worst way.

[ThomPete]

Exactly. I found that most clients care way less about "world class" quality than they care about delivering on time since their job is rarely to deliver quality but rather simply to deliver.