Any advice for BLW

My son is 6 1/2 months. The purée approach hasn't gone well and now my son is refusing to open his mouth and crying and turning head away. I don't want to put him off food. I'm scared of him chocking on food. Today tried offering various food and he barely put it in his mouth. Although he did put a whole piece of cucumber on his mouth. I cut things up big so he wouldn't choke but he managed to get it all in. Am I best to cut things smaller. If I was to try him with a baby bell cheese would I leave it whole or cut it small?