Should new windows be set back?

[Custom45]

Hi,
Just building a small workshop in garden, nothing substantial. Going to fit a couple of small uPVC windows but want the external walls rendered after with silicone render. Should the window frames be set back slightly to form an external reveal that will then be rendered? Or should they be fit flush with the wall and the rendering will form the reveal? Thank you

 

[jj4091]

Fit one loosly then see which looks the best option.

 

[endecotp]

Setting them back means they are less exposed to the rain; there have been threads on here where windows are leaking and the conclusion is they should have been set further back.