My DS is 19 mo and we did a combination of BLW and purees/mashed food from 6 months. To be honest, there are days that he just doesn't eat much, like yesterday, and it does worry me but I try not to let it.
If there is no problem with chewing as you say, you could just given him family foods and leave him to it. He won't starve himself. If the cold-turkey approach is too much for your nerves, you could perhaps start by offering one meal a day as family foods and mash the others.
For example breakfast could be the usual porridge/weetabix/muesli etc, etc Then you could try non-mashed sandwiches, veg sticks, cheese sticks etc for lunch and do mashed at dinner time. You could also try to let him help himself at dinner time with his mashed foods by giving him a spoon and letting him go for it.
Feeding toddlers is a very messy business from what I can see and a lot of food does seem to go to waste but they do need to learn to help themselves.
I have found that it helps to think of mealtimes as learning and exploring experiences and I basically let DS 'play' with the food. He likes to touch, feel, smear, pretend feed me and taste his food for himself. Mostly he will eat some of it until he is full and then play until he is bored and asks to get down. Sometimes he won't even look at the food.