Will i be okay to return to work before anti-depressants kick in?

It depends on degree: It depends on the degree of depression, if you are not able to function and just started antidepressants you may have to wait few days before you feel full effect of the drug ask yourdoctor or psychiatrist when you are fit to go to work.

No plan: Not usually. Too much stress involved in workplace and you could easily have a relapse even before you are on medication.

That totally depends: On degree of impairment. Most people who are depressed are still able to work. If you are not able to function than you will need to wait until you have some improvement. As previously stated however, most people can still work with major depression.