There is related Supreme Court ruling of 2013
It directs you to invoke the Fifth Amendment "before arrest" (just how are you supposed to manage it - on the run from cops?). It denies you your constitutional rights, otherwise. And even your silence would be used against you in the court... if you didn't invoke the Fifth Amendment "before arrest", again...
I suppose, the meaning is - they give you few seconds while getting you handcuffed to invoke the Fifth. And that's it.
If you aren't arrested before they question you, they may argue, that you may not invoke the Fifth... yet. Too soon. Than - too late...
https://disqus.com/home/channel/geopolitics/discussion/channel-geopolitics/the_arrest_of_chelsea_manning_unconstitutional_us_grand_jury_system_global_research/#comment-4373081474