To make a cake, should preheat according to the quantity of Batter? 

OR  How to preheat according to the quantity of Batter? Please Help

30 minutes is the longest/safest pre-heat to be sure that everything is sufficiently hot/stable enough --

other than that i'm not familiar with pre-heating according to what item you are baking -- pre-heating is just to regulate the temperature -- you can put anything in there after that -- some ovens get turned on after the item is placed inside -- 

so pre-heat to the temperature you want for 30 minutes -- no worries -- best to you

maybe you mean how long to bake a cake because amounts of batter differ? 

there are many different factors to getting a cake baked peculiar to each location, oven, recipe, size, shape of pan -- there is no one formula for baking a cake the correct length of time 

http://www.wilton.com/wedding-cake-guide/cms-wedding-cake-data.html

this is guide but nothing is definite -- you could get a cake/food thermometer though

https://www.amazon.com/Habor-Instant-Read-Meat-Thermometer/dp/B01DISPQJ0/ref=sr_1_1_s_it?s=grocery&ie=UTF8&qid=1513182786&sr=1-1&keywords=Habor+Instant+Read+cake+Thermometer

*that first link is a guide but nothing is definite

i like this one -- no moving parts -- the tip turns red when the cake is done:

https://www.amazon.com/Nordic-Ware-Reusable-Bundt-Thermometer/dp/B000237MI8

Huh!  I never heard of this cake thermometer -K8memphis .  Read the reviews on it and apparently it's a pretty neat tool for "deep" cakes.