Before your interview, make sure you have a start date in mind for the new employer. Whether you need to give two weeks to your previous position, or are unemployed and can start right away, be prepared with an affirmative answer.
If you are currently working, you should always show professionalism by offering 2 weeks' notice to your current employer. No hiring manager is ever impressed when they hear 'I can quit my job today and start tomorrow!' Show that you are professional and reliable in all situations.
"I am currently unemployed and am willing to start as soon as needed."
"I am currently looking for a career change within a 4 week turnaround timeline."
Sales answer example
"I would need to give a customary 2 weeks' notice to my current company so that they could choose if they want me to stay and transition accounts or make it my last day. But, out of courtesy to them, I need to let them make the decision."
Retail answer example
"I would need to give my employer 2 weeks' notice. Due to my length of employment, it is possible that I may need to work an additional week, if they were to request it of me to aid in the transition to the next manager, but I am available immediately following. Can you clarify your timeline for me?"
Marketing answer example
"I would need to give my current boss the courtesy of two weeks' notice, but I am available any time after that! Looking forward to getting started, honestly."