You're right when you talk about "carving out" time. You won't get any significant blocks of time for reflection unless you plan for a quantum of uninterrupted time. I suggest you go for 90 minutes at least every two weeks. Airplanes are great places for this.
The keys to make this work are that you take enough time, that you capture your musings and ideas, and that you have a place to put them that provides an ongoing record. A spiral-bound notebook or pad is good.
With all your ideas in one place you can go back and elaborate on older ideas as well as enrich new ones. There's one more key to getting this to work. At the end of each session ask: "What should I do now?" The answer should be sometime observable by others such as a phone call, an email, a bit of research or a conversation. There should always be an action outcome.
In addition to the sessions you schedule, there will also be "creative" times when you'll get ideas while you're doing something else. Usually that will be something that doesn't involve your mind such as driving, taking a shower, walking the dog, or exercising.
When you get an idea in one of these situations, you need to capture it. Otherwise you will not remember your brilliant insight and it will flit away like a butterfly on the wind.
Use any simple system that works for you to capture your ideas. Some folks carry an "idea pad" with them. I use a small digital voice recorder.
When you have your next scheduled session, one of the first things to do is make sure the ideas you've had and captured get noted in your permanent record.