@ChanSmell86 ooh you are getting a battering.
Walking/reins/buggy - take your child out, let them walk a bit. If they run off, use reins/wrist strap. If you are putt for a long time, or need to get somewhere quickly, use the buggy! I still used it as dd was approaching 4 for a long beach day out.
Nappies - well, you can try at 18 months, but it'll likely take you months. DS was potty trained at 2y 9m, he was ready and I was pg and didn't want 2 in nappies - even then DM was surprised that I was trying to PT a boy before he was 3. Took about 3 weeks. DD on the other hand announced one day when she was 2y 3m "pants today", and was done and dusted, day and nights, weeks and poos in 48 hrs.
Every child is different!
I lived 100s miles away from my family when I had my dc, I didn't know what was what. I had a brilliant HV though, and made friends at parent baby groups. Great for a bit of support, great for having an idea of what the "norm" is for children around the same age as mine. Still the case 15 years later now they're grotty teens.