Your day is going to look different from anyone else's, based most of all on your son's internal clock. Don't expect your newborn to follow any kind of routine for a couple more months. Feed her when she is hungry, put her down when she is tired and hold her when she wants to be held. My babies were 12 weeks old before I started observing any pattern in their behavior. Eventually that pattern settled into a routine, which became a (loose) schedule. The scheduling is for you and your toddler, NOT for the baby!
I don't think it's the best idea to have a set-in-stone schedule; however, routine is really important, especially for toddlers. My best advice is to write down what you guys are doing for a couple days and see what kind of pattern you notice. Once you have a routine, try it for a week or so and see how it goes. If it doesn't work for your family, tweak it until you figure out something that works.
One thing I have noticed with my girls is that if I wait for them to tell me that they are hungry, they are already acting like little monsters. The best way I have found to head off defiance, temper tantrums and whining is to have well-fed, well-rested kids. We still have plenty of defiance, temper tantrums and whining, but it's better than when they are hungry! I get breakfast ready first thing when we get up. I try to make sure that it is a high-protein breakfast whenever I can. "Cooking" breakfast (instead of pouring cereal) is more work, but starting the day with protein in their bellies makes a world of difference for everyone. (Protein is broken down slower than carbs, so it provides a steadier, more reliable source of energy without rapid swings and dips in blood sugar.) Two hours later, I try to offer a carb snack like some fruit and crackers. For lunch, we usually have sandwiches, fruit and cheese. After lunch, everyone rests for an hour or two. The baby takes a nap, the 4 year old stays in her bed to rest or read, and I stay either in bed or on the couch reading, knitting or napping. Two to three hours after lunch, we have another snack. They might or might not watch a movie in the afternoon. I try to limit TV time to a few movies a week (or equivalent TV time). I try to get a nutritious dinner into them by 6/6:30pm, then cleaning up toys, bathtime, books, snuggles and bed.
Truthfully, sometimes our day looks NOTHING like this! Some days we sleep until 10, eat cereal for breakfast, don't have lunch until 3 in the afternoon, and don't go to bed until 9 at night. Life happens, and I think you have to be flexible enough to live it. That being said, I try to keep my kids needs in mind. If we are going to run around all day, I try to make sure we have snacks in the car, including some fruit and protein, rather than all crackers. I try to have some knitting or a book in the car, so that if they fall asleep between errands I can park the car somewhere and read/knit while they nap in the van. I know people who are so tied to their schedule that they miss out on any fun spontenaeity in their lives. Like everything else, I think it's a balance. Try out a routine for a week and see how it works for your family. If it doesn't work, change it! Sooner or later you will figure out something that makes your day easier rather than harder.
Best of luck,
S.