We did BLW. Like someone else said, it's really the idea of only offering them finger foods from the start and letting them self-feed, skipping the purees. But there's no reason you can't start making the switch to finger foods now even if you've been doing TW up to this point. It's really easy and doesn't need overthinking. Just offer whatever you would eat yourself (minus added salt, sugar, honey and whole nuts) in whatever set up you usually feed her. Pasta, sandwiches, pieces of banana or other sliced fruits, grapes, blueberries, yogurt, steamed broccoli florets, rice cakes with hummus/nut butter/mashed banana, toast with anything on it, mini pizzas, curry and rice, cottage pie, soups with bread and butter. Really anything you eat as long as you avoid added salt, sugar, honey and whole nuts (and probably too much chilli for now). Most of it will just get mushed around and chucked on the floor to start, especially if she's used to being spoonfed. But that's fine. She'll eventually work out what to do. You just can't expect too much too soon. We started BLW at 6 months and though my daughter ate solids and they were obviously coming through in her nappies after about 2 weeks of doing finger foods, she didn't really eat in any quantity until about 9 months. So that's about 3 months and that's with a baby who hasn't already learned to be spoonfed. It will just take time. Offer lots of interesting finger food options and sit back on your hands for a month or two and just let her play. She'll get it. My daughter is almost 2 now and is the most amazing eater. She eats so many weird 'non-kid' foods, like pickled onions, toasted seaweed, olives, curry, smelly cheese, etc. But it really did just take being patient and letting her go at her own pace.
(It's worth adding, I always found avocado to be really hard for my daughter to eat. So you might just need to try something easier. It's very slippery and it's a weird taste and texture anyway. I found it was more acceptable to her if I mashed it with banana and spread on toast fingers).