arbor,
Fill out your profile a little more and give us a location to give you an idea. Jay, Fish and Sight all give good parameters imo. Fishing the Berks Co. area streams this time of year I like late evenings. I can leave the house at 7:00 be suited up and fishing by 7:30, fish until 8:45 or so when they turn off and have a great "day". Conversely I can drive a couple of hours, put in 10 hours and catch the same number of fish +/- a few. I personally find the evening fish to be much more forgiving, as their guard is down a little. Also, if I hit an AM trico hatch I will fish, and fish, and fish even though fishing a stream like the Tully at 11:30 AM in July is almost pointless. If I hit the stream at 7:00 PM there is a definite ending point of the trip (for the most part).
A lot of factors :
Location
Are you a dry fly or nymph purist or are you willing to mix it up?
How do you like fishing tiny flies on long, fine tippet?
When CAN you fish?