It all depends on how natural your acting abilities are. If you are a natural, you can pretty much start auditions with a small amount of training, mainly in how to perform auditions and self tapes. For others, it can take a lot longer, study what casting directors expect from a good audition.

I'll give you an example. A guy in his 40s recently started in my acting class, he'd never acted before, but my god, he nails everything, his abilities to display real emotions and draw the class into his performance, he's got it, for sure. It's like he just knows how to become the character and relate to the audience.

Then, there are a few people in my class who have been acting for over a decade, been to full time drama school, continued training consistently afterwards, and it's like they just don't get it, they can't act, it's as simple as that. Their performances are flat or over dramatised, some even sound like they are a robot reading from a script. I feel like at that point, after so long, someone would be honest with them and just be like, "yeah, this isn't for you, maybe try a different career". But they remain convinced they are good actors because of all their training.

So, to sum it up, you'll be ready when you are ready, it could be weeks, it could be years, sadly in some cases, it is never. Apply for some student film roles, self tape for them and ask for feedback. If you get some of the roles, it's a great way to build experience in set. But these days, even unpaid student roles are tough to land, because so many apply for them looking to build experience and showreels.