Hi garden, just seen your question. How old are yours now? And do you have follow-up care from a paediatrican?
Mine were 10 weeks early, which is quite significant, and we have regular follow-ups. Their doctor said we should wean at 6 months actual, not corrected, just as Dream says. They really surprised me actually because they looked no where near ready - not sitting unsupported, not picking things up etc - but once I showed them food they wolfed it down! So for us weaning went really slowly - ages on really soft purees, then gradually introducing more flavours and textures.
We had to start in an upright-ish bouncy chair, then in bumbos, then highchairs, but only certain ones - we had IKEA Antilop with the inflatable inserts, but rolled up towels etc would still be good. I remember in June, so they were 10 mo, we went on holiday and couldn't use the wooden high chairs in the hotel at all and had to run out to Argos to buy some!
They were still only just beginning to pick things up around then too - once they were in high chairs I'd always put something on their trays, but they'd just sniff at it imperiously! Within a few weeks it had clicked and they could happily munch through some finger foods, but tbh some textures are still quite challenging. Our doc says that's quite common with premmies, but it could just be that DS is a fussy so-and-so!
NOt trying to put you off, by all means try BLW and I hope you have a lot more success in the early days than I did, but don't lose heart if they don't seem to be going for it. DS's appetite was so far ahead of his motor skills I think it would have been really cruel to persevere - he clearly wanted food, but he wanted me to shovel it in as fast as I could!