Generally, formula intake at that age should be around 32-40 oz. As for the amount of solids, start with 1 teaspoon and go from there. The key is to ensure that formula intake doesn't drop, since that should remain your LO's main source of nutrition for several more months. If you see a decrease in interest in bottle feeds, reduce the amount of solids. I preferred offering bottle/breast first to ensure Tyler was filling up on what was most important, then offering solids about 1 hr later when he had a bit of an appetite. It depends on what works best for your LO. Some folks do solids first, then breast/bottle; others do it all at the same time. There's really no right or wrong way to go about it.
I'm not going to be much help on how to work solids into your LO's current routine...we didn't start solids until 6 mo, so Tyler's routine had more awake time to work with. I'm not sure how you'd work it in with a younger baby, hopefully someone will have some advice for you!