I have found that giving God the first hour of every day is an excellent practice. Not only does it honor God by giving Him the "firstfruits" of the day, but it is the most helpful thing I've ever done in regard to my own spiritual growth.
Before I do anything else, I spend an hour in prayer, Bible study, singing, and meditation on God. In order to do this, of course, I have to get up an hour earlier than my schedule would otherwise require. I do this seven days a week. I don't always get up at the same time every day, but on any given day, whatever time I would "have to get up," I get up an hour earlier than that -- and give that hour to the Lord.
Not being a "morning person," this is a very difficult thing for me to do. Even so, I have made it a matter of commitment that I will not allow myself to do anything else until I have devoted myself to the Lord for an hour or more.
Some individuals might practice a similar discipline at the end of the day, staying up an hour later than they normally would and giving that hour to the Lord. Either way, there is a great benefit in making the sacrifices necessary to devote a certain time exclusively to the Lord.
Personally, I believe the beginning of the day is preferable because it gets the day started off in the right manner. It puts into practice our preaching about what should come first. It says, "Lord, I thank you for this new day. I will not embark on any of this day's activities until I have worshiped You and learned from Your word. Lord, I give this day to You."