Hi
@Lucielu, If you type in 'Switching to Fiasp',' starting Fiasp', 'Fiasp' into the question box right hand side upper page on the Forum page you can find the threads that already exist on this topic. I assume you are particularly interested in insulin injections rather than use in an insulin pump, but there are threads for both.
If, despite this, you still have questions then by all means please ask further.