You are advised to do this so that you can build these fees into your financial planning. For entity applications the figures will feature in the start-up costs for the firm and the month 13 costs in the cashflow forecast that you will need to produce as part of your application. (Please see Stage 7 of this application process).
Now might be a good time to start thinking about what your Professional Indemnity Insurance premium might be as it will be the other major cost for you to build in to your financial planning alongside your regulatory costs.
This is covered in more detail in Stage 8 but you might want to think about obtaining an initial indication now.