Server-Sent Event: Is there a way to measure timing on the first message?

[songohannyc]

Question

Hello,
Is there a way to just measure timing on the first message received from Server-Sent Event? If not, is anyone aware of any library that can do that? Thanks.

Reference: https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events