The initial start up is time consuming. After that, the time you gain by not having to look through your "stuff" is more than gained back. The weekly review takes about 2 hours; however, during the week that time is redeemed by increased productivity and effectiveness.
I never think about the time it takes to maintain GTD. As the system helps me stay on target and feel in control. Before GTD I never had the sensation of having lots of time, mostly I felt out of control and frustrated.
There's two ways to go at GTD, and neither involves pulling yourself up by your own bootstraps. You can implement it all at once, in a big clean sweep of everything, or you can bring in bits and pieces at a time. There are advantages to both approaches, and disadvantages.
The clean sweep is good because it gives quick results, and changes your whole system at once so it all fits together; bad because it takes a concentrated amount of time to set up the system, and because you're trying to learn a lot of new habits all at once.
The sneaky approach is good because you're working on one habit at a time, and it doesn't take much setup time; bad because results are more gradual, and because you're still working with a backlog of work hanging over you.
It's Stephen Covey's "Sharpen the Saw" habit. If you're trying to cut down a tree with a dull saw, you'll be better off in the long run if you stop sawing for a little bit and sharpen the saw even though you'll make less progress in the immediate moment.
Any new process takes ramp up time. I have one question for you:
Are you willing to commit 30-90 days to get the process nailed down?
How long it takes for the process to kick in depends on the following:
1. Do you like your life like it is? Or are you willing to take time to make changes in habits now that will help you be more relaxed, more productive, and more prosperous?
2. Are you willing to be patient with the process and yourself and break things down into baby steps? By that I mean can you work through one chapter at a time in the GTD book until you feel comfortable with it?
3. Or can you use the Ready for Anything book, and work through one of the 52 ideas until you are comfortable with one idea and move onto the next?
4. Even if you only do a few of the things to get started - collect everything into one in basket and process them; and do the weekly review - you will see a big improvement in your life.
I would also sit down and do the following:
1. Write a mission statement for your career/life. What is it you want to do or be? If you are a computer programmer or web designer - do you want to be the must successful and prosperous one there is? Or do you just want to collect a paycheck and do the bare minimum at work? If you want to be the top in your company or in the industry, then make a mission statement declaring your intentions.
"I am a highly innovative and creative web designer who contributes value to the industry. And I am paid handsomely."
2. What are your 1 year, 5 year, 10 year, and 20 year goals? Set them down on paper for health, wealth, career, love and spiritual. This will keep your life in balance. Check to make sure your goals are in line with your mission statement. Then from these high level goals, break it down into baby step goals you need to complete each year, and baby step tasks you need to complete each day, week, month, etc. What do you have to do now to be the most innovative and creative web designer, chef, teacher, etc.?
3. Once you have a blueprint of your mission statement and goals in place, remember they are flexible and can be changed and tweaked as needed.
4. Use that mission statement and goals with GTD to help define what is important to you to work on in life. If you now where you are headed, then it is easier to use GTD. You will find yourself working on what's important to your mission and letting unimportant stuff - web surfing, overeating, overtopping and other time wasting activities - fade away.
Remember, if you have no direction in your life, then somebody else will just take your life and whip you around like a yo-yo for their own purposes.
I strongly recommend "bootstrapping" the new process by making it a project, e.g., "adopt GTD" or "GTD is up-and-running." What's the next action? Almost always it is working on the next chunk of backlogs - paper and email. These are very important to clear; otherwise they'll drag you back to old habits.