Is there a gap between issue of EAD and Starting employment

[abhishes]

I have applied for an EAD and am waiting for its arrival.

I also started looking out for jobs. I was told by an employer that there is usually a 90 day period between the issue of EAD and the start of employment.

I really find this puzzling... what is the rationale behind this? I should be able to start working immediatly as the EAD is in my hand. Why should there be a 90 day gap?

since this is coming from a an employer ... perhaps there is some substance behind this.

[immihelp]

You can start working as soon as you get EAD approved. There is no waiting period.