In normal python, everything is compiled from top to bottom, so if you have imports at the top they will load first, then your classes or functions will compile etc. (If that is what is next).
Also in normal python, although it is considered bad form, you can do an import at any time in the script, and if you call it multiple times, for instance as if it were in a function, each time it was called.
There is a slight overhead where it checks to see if it has already been imported, but other than that, it skips importing it over and over. (which in your case might save time).
I have not noticed many, lets call them ‘edge cases’ regarding skuplt, so I assume this should still work as expected in the client side of anvil.
I also wonder what happens if you put the import inside a context manager:
with anvil.server.no_loading_indicator:
import this # For example
…would it import while still letting the user interact with the page?