As on any social media channel it all depends on your audience, when they are usually online for you to get bigger reach. If you are just making your first steps in this, the good option would be to post in the evening. Usually it's the time when most people get off work and do some endless scrolling.
How? Well, right from the Pinterest pins creation studio or by using some tools like Tailwind. Figure out where you want to take your audience, do some stylish pins, you can use Canva for that.