According to the Laravel documentation Estimated Upgrade Time is about 1 Hour.
Important Laravel 5.5 require PHP 7
Update your laravel/framework
dependency to 5.5.*
in your composer.json
file. In addition, you should update your phpunit/phpunit
dependency to ~6.0
.
The Pusher event broadcasting driver now requires version ~3.0
of the Pusher SDK.
Offical step by step guide for upgrading Laravel 5.5 from 5.4 version