If you have an office then you will want to make the most out of your space to allow you to get a certain number of staff in and all the equipment / filing space you need.
Planning out your office is very important and you need to consider not only the practical side of it but also health and safety plus fire regulations to make sure you adhere to all of these. It may be that you only have one or two employees at present but you will need to consider if you may need to expand in the future and if the premises will allow for this or if you wold mind if you have to relocate.
You may wish to hire an office bigger than you will initially need so it already has room for you to grow your business as and when you need to.