New floors are most affected by humidity. During the dry winter months, use a humidifier to keep the floor tight. During the humid summer months, use an air conditioner or dehumidifier.
As far as vacuuming goes, remember NOT to use a vacuum with a revolving brush and when you do vacuum, move with the grain.
If you have pets and active children, you may want to coat as often as every six to twelve months. If the floor sees very little activity, it can go for years without any work. The best overall guideline is three years because you don’t want the heavily used areas to wear through or else the whole floor may have to be resanded.