DS didin't really start solids much at all atil about that age.
there are a couple of things you can try, either 3 bottles with a small amt solids after each, or just 2 solids feeds, in between the bottles.
I didn't start DS on 3 feeds of solids a day until about 9 months, but then he wasn't overly interested in it either.

what time does he wake up in the morning?
all you can do is try your best. if he is hungry he will let you know, and if its not 'time' to eat then so what.....adults don't always get hungry to a schedule, so while a routine is great, it can be more around the sequence of the events than the timing of them.

I hope that makes sense.