This is expected behavior. After installing and activating a plugin, you are supposed to Rebuild & Restart. There's a special button in the ACP to perform this.
Then there is no problem. Thank you for your answers.
I've got an instagram embed going but not sure if you guys want it ?
The front page as well in the latest posts doesn't show the picture/post until you reload the page. Noticed this happens with twitter embeds also.
Yes, please. This is a good plugin