There is no grace period for H1B, not a single day. If you leave your H1B job, your H1B status is lots immediately. It might be possible to apply a new H1B bas

There is no grace period for H1B, not a single day. If you leave your H1B job, your H1B status is lots immediately. It might be possible to apply a new H1B based on your YC company, or obtain other work authorization like EAD to be able to work in the US.