The amount of time I have for reading varies enormously (as does the amount of time I have to post on my blogs). I used to sign up to various reading challenges and bookcrossing release challenges which meant that I had to finish reading books quite quickly. At that stage I always read a chapter after lunch and a chapter at bedtime, no matter how long the chapters were. Then I'd read extra if I was sitting in a waiting room anywhere or waiting for my parents to finish their afternoon nap before we did something as a family. Then the amount of time I had for reading got less because of work, so I'd stick that plan at weekends and read for up to half an hour at bedtime depending on how early I got to bed. Eventually I ended up getting to bed too late and had to drop my reading challenges (I didn't have time to post the results anyway). So then, with the pressure off, I began to just read when I felt like it. No I have no set times for reading, I just do what I feel like when I feel like it. I do try to do a little bit each day though and tend to read for at least 10 minutes at bedtime to help me get to sleep.
As for what I read- again I used to be restrained by what I needed for my challenges. Now, once I've read any bookcrossing rings/rays or library books, I read whatever I'm in the mood to read. All my TBR books are laid on my shelves in roughly the order I got them, so I tend to start at the oldest of these and work my way along the shelves until I reach something that I fancy reading. If this proves to be something I'm not comfortable reading at bedtime I'll then pick up another book as well for then. Ocassionally I make exceptions to this system if I want some books for a specific bookcrossing event, making sure that I read some I'm willing to give away instead of those I know are definatly going to go into my permenant collection.