For determining what one can afford computaionally, see e.g.:

https://stackoverflow.com/questions/22443041/predicting-how-long-an-scikit-learn-classification-will-take-to-run

https://www.reddit.com/r/scikit_learn/comments/a746h0/is_there_any_way_to_estimate_how_long_a_given/

Lähetetty Windows 10:n Sähköpostista

Lähettäjä: lampahome
Lähetetty: Friday, 25 January 2019 3.42
Vastaanottaja: Scikit-learn mailing list
Aihe: Re: [scikit-learn] How to determine suitable cluster algo

Maybe the suitable way is try-and-error?

What I'm interesting is that my datasets is very huge and I can't try number of cluster from 1 to N if I have N samples

That cost too much time for me.

Maybe I should define the initial number of cluster based on execution time?

Then analyze the next step is increase/decrease the number of cluster?

thx