Put finger in mouth, ****, take out and hold in air.
Then make a number up and double it.
How longs a piece of string? lol
Once you have a lot of experience in doing them then you will be able to figure out the time it takes and it's all based on your time.
Figure out a cost for your time then use that as a base.
It depends what tool as they all have differences, to what standard, what complexity of footprint & symbol, what information you have and are you going to double check your work afterwards?
It takes me 5 minutes (max) to make a (part) symbol & component for a resistor\capacitor as the symol & component are already made or just need a little changing and then I tie them together as a part. Then another 5 minutes to re check everything.
A Xilinx 1760 pin FPGA takes me about 5 minutes for the component (if its a plain x by x pads) longer if there are pads missing. The 20+ symbols can take a couple of hours as I need to get them in the right order (something the person wanting the part never specifies first!) and having a text file (in xcel) usually helps speed this up.
Then it can take all afternoon to check.
So depending upon the complexity etc times can vary.
You need to make the best use of the tools available, like footprint wizard etc, follow consistent standards and always check your work to ensure that its 10& correct - any mistakes can be costly and will cost you a customer.
What PCB tool are you considering using?