Can I change permalink structure mid-blog?

I want to change my blog permalink structure from, for example:

https://blog.theflowerraj.org/?p=1629

to something like:

https://blog.theflowerraj.org/2011/09/23/sample-post/

Should I leave well alone, use a permalink plug-in of which there seem to ne many?

Or should I make the change in WP Admin?

Thanks in advance,
Nico Morrison
London UK.