Help with the Onload: hook ---- proper onload function

I was asking about getting help with “Using IFrame API, need to refresh page to see Jitsi”

where it was kindly pointed out "there is onload hook in iframe api options: IFrame API · Jitsi Meet Handbook (thank you).

What would be the proper onload function to prevent the User from having to refresh the page to see the Start Meeting’ button/box/field?

Any additional help is appreciated.