There is no need to get to the station extra early because you will travel with an international train. 

But Berlin Hbf is a big station with two distinct levels so arrive in time to find the platform! 

Not needed :)

General Suggestion get seats on the left side for a nice view after Dresden :)
and visit after the Czech Border between Bad Schandau/Decin the Czech Dinning Carriage they still cook few meals fresh on the train https://www.jidelnivozy.cz/uploads/menus/foodMenu/3.pdf as the Czech dinning carriages have then “Happy Hour” with cheaper prices

The train at 9.16am have a Hungarian Dinnig carriage :)

Not just that: most pax on that train boarding in B will be domestic-the train makes several stops In DE, of which DD is the biggest, so there simply is no difference!

ONLY train wanting that is this €* to/fro LON,and in ESpana they also do airline style cursory luggage checks for the hi-speed trains.