It took me a year to complete the book. That's with a few breaks in between some a week, some longer, once 3 months. I say, slow and steady with solid reviews is the best. That's how I finally finished. I just wish I had done that from the beginning. If you can do 20 a day, which I think is still a fairly quick pace, you should be near the end of the book by the end of 3 months. If you get tired of it or need to take a break because life gets in the way, it's not really that big a deal as long as you maintain your reviews which should be the quickest part of the method.
I found it very effective to make physical flash cards when I was going through the book. I would say doing 20 new kanji a day could take from one to three hours depending on how fast you are at creating and visualizing stories, making the flashcards, getting the images of the various radicals in your mind, etc. Some sections of the book are easier than others. I think it's important to spend a lot of up front time with the kanji and their stories before moving on. It makes them stronger. I did this well with the first 700 kanji. I hadn't heard of SRS by that point, and, partly because of winter blues/culture shock and partly because of the hassle of dealing with 700 floating flashcards that I hadn't developed a system for reviewing, I took my 3 month break. But because I had spent so much time making the cards and stories in the beginning, I was able to recall 90 percent of those first 700 kanji with no additional review. So I highly suggest investing time up front to save you time later.
You seem to be cautious now about going too fast. I think this is important. Some people have managed to make it through the book at a quick pace, but for me when I tried to speed up at the end, I wasn't able to remember the kanji as well. Also, I think going straight from looking at the book, to making a visualization of the story, to putting it in your SRS is not as helpful as physically writing out the kanji and the story on a flashcard, studying it and recalling it a few times before putting it in the SRS. Also, it gives you a way to take your study on the go.
I would try setting a certain pace for a week and see how much time is required daily by the end of the week when the reviews start piling up (This is assuming you are going to use an SRS). If it's manageable, continue at that pace. If you feel you can increase the pace, do so a little. If you it's too much, decrease a little. Keep adjusting until you get a nice pace. It's ok on some days to do less or no new cards as long as you're maintaining reviews. But on days when you have extra time, I suggest restraint in adding lots of new cards. Because you may have time that day to add them, but you may not have time in the subsequent days to maintain the reviews of that extra load of cards. This is something I struggled with.
Of course, this is what worked for me. Each person has different strengths and weaknesses. You should know your study habits and your lifestyle and adjust RtK accordingly. But a big must is maintaining reviews throughout. Also, the above is for someone who is interesting in setting goals or a daily routine to help motivate herself. Others have found it more pleasurable to enjoy the experience of creating stories and learning the writing of the kanji rather than focusing on numbers and deadlines which can be stressful even if you choose them.
Whatever you do, try to enjoy the experience. Have fun with the stories. Pat yourself on the back when you've hit various benchmarks or when you learn a particularly difficult looking kanji even if it was easy to learn. Don't be embarrassed to show off the kanji to your friends and family. As you go through the book and get to know the kanji, pick your favorite. So let the very first kanji be your favorite. Then when one you like better comes along, it's your new favorite. Put a picture of it on your wall. Sew a pillow for it. For a kanji you don't like put it on a dart board and use it for target practice. Whatever you need to do to maintain interest and enjoyment, do it.
Bonne chance Flocon de Neige! Je souhaite que tu t'amuses en apprenant les kanji et que tu aies du succ?s.
