I always remind myself "15 minutes a day is better than an hour every three days". But in order to prevent getting over-stressed about time and how quickly you're learning, you have to put your ego aside and simply stick to a schedule of learning a little bit of each subject every day.
That means limiting yourself when you want to go on a binge just as much as it means making time to get your 15 minutes in. Three days of binging on a subject can start to build pressure that you should maintain that level, and that's not sustainable.
Small amounts of new knowledge, every day, until you've hit your goal.
No matter how old you are, you still have plenty of time to take things slow.