I would suggest if in case you have financial backup and have an adequate funds with health insurance, try to go for 100% to your MVP. I'm doing that currently.

It would be hard, exhaustive to switch from day job to your MVP. One of them will definitely suffer. Your mind and body will constantly thinking about your MVP while you will be in your day job.

Multitasking is good but for a shorter time. It shouldn't be considered for long term. Read this article, https://www.verywellmind.com/multitasking-2795003. And lot of research has been done in that domain.

Again, if you don't have adequate funds to run at-least for a year or two, do not leave your day job.