I've gotten a response in under a minute, and I've submitted applications and have never heard back. My experience is that there is no way to know.

It usually takes a couple of days, but yesterday my sister in law received a call before she'd even submitted the full application! She'd only put in her name and number and was still filling out experience and questionnaire. Pretty crazy.

It depends on the employer. Some are really good at getting you a quick response, and some are terrible about not ever responding.

I've experienced anything from 2 hours to never. They have no obligation to reply. But on average, based on my experience, they generally reply within two weeks.

It should be about the same time as paper form. You should call the potential employer to follow up. It shows you take initiative.