Congratulations on your new Scamp, you will love it.
I would wax the trailer as soon as you can. Waxing a new trailer has 2 distinct advantages, first it protects the surface and prevents oxidation and the effects from the sun and elements. Secondly it makes cleaning the trailer, especially bugs and other road debris much easier to clean off.
Although there are many opinions on wax and exterior care I prefer to use products designed for the fiberglass marine or boat industry, these products are designed to be used on fiberglass and are also designed to stand up well to extremely harsh environmental conditions. My preference is the Meguiar's Flagship line of products.
https://www.meguiars.com/en/marine/products/
