Agree....Take the written...get it out of the way so you can concentate on the Practical.

Technically speaking, the age limit for the written is tied to the age you can take the practical, though, it is not in the FAR's. For example, to take the ATP Practical, you must be 23 years old.

You can take the written exam for the ATP when you are 21.

21 years old + 24 month validity of the written = 23 years old for the Practical.

You cannot take a written examiniation unless the results will be valid for a period of time in which you can take the practical.

This comes from the FAA, as I needed guidance while I was running a 141 school.

The same logic goes for every other rating/certificate.