I would look out for signs of readiness and maybe when doing nappy changes explaining to little one what to do when wet or dirty.
This is quite useful I think. https://eric.org.uk/potty-training/ We've been putting lo on the potty since 6 months. I'd recommend keeping it as relaxed and fun as possible. We read books, do puzzles etc. Start before/after naps/morning wake up/after meals. Now we've been doing it a while we've also taught her the sign for potty so she now asks to go so we don't really put her on at specific times just when she wants to go. Recommendation for a potty is the IKEA white a green one. Stable, quite a high back to support and easy to clean.
@Becky ooh what's this? I've never heard of it x
@Jess It looks like this, you can get them cheap secondhand. Essentially instead of sitting them on the potty and hoping they go, you wait until they are peeing (so naked that day and watched closely) and then rush them to the potty. In theory it helps them learn their cues faster and associate them with using the potty.
Use tiny potty book by Andrea olson for 18mo +, its simplified compared to oh crap which is for 20mo+. I started elimination communication at 12 mo which was 1 month after walking but 18mo is too old for that. He's getting the hang of it really well though so should be much easier when we start potty training which I'm also trying to plan avoiding big events like moving or starting nursery. Website look up ERIC.
We are using the Oh Crap! book and method, it's meant to be much quicker although it does suggest waiting until 20 months as a minimum. We are three days in and he knows when he needs a wee, knows it goes in the potty and loves flushing it down the toilet afterwards.