can we use each of them(very-so-too) before the soon?
I cannot think of any instances where you are able to use ‘very’ immediately before ‘soon’.
The others can be used in the correct contexts but aren’t interchangeable.
It’s too soon.
I don’t think you should exercise so soon after eating.
It’s fine to use ‘very soon’, it means ‘in a moment’ (src.: thesaurus.com/browse/in+a+moment ).