The Plant-A-Genda product will keep your seeds safe in the correct month of planting, however it makes life easier if you also use a calendar to record when you planted those 2 rows. You are going to plant another 2 rows, two weeks later, so calendar entries help with this.
If possible, it is good to have 4 different beds, so that you can do 4-yearly rotations, thus beans etc. will have been planted in 4 different beds in 4 years, which stops a build-up of non-beneficial bugs.
Writing down all the plantings you do on a calendar sometimes means that there is little space for anything else on that date.
To minimize this problem, put a coloured dot on your calendar, and have a Garden Diary in which to enter the plants you have sown. Looking through a Diary to find an entry is usually very very frustrating, and this is one way of dealing with that problem. This way, you see the coloured dot against a date, and then turn to that date in your Diary.
Once the seedlings have come up, take digital photos, and have a Garden folder that you put them into. This will help you identify plants more easily, and tell you what you planted when, for the following year.