Basics things about Texture Atlas NGUI

So i have some basic things to ask about TextureAtlas i.e Performance issues

using —> NGUI 2.6.1 and Unity 4.3

  1. I have loaded all my atlas at runtime i.e in splash screen. Is it a good way to do it ?
  2. Which one is better to make 4 atlas of 1024 X 1024 or 6-7 atlas of 512 X 512 .By making 6-7 atlas i can segregate more easily i.e 1 atlas for main menu,1 for game over but in case of 1024 my main menu atlas contains some of my game over texures also.
  3. Is it good to make 1024 X 2048 atlas or above it ?

The more atlases, the more wasted space (and therefore texture memory) between images, so try to stuff as much as you can into each. Don’t go over 2048x2048, some mobile devices do not support 4096 and larger textures.