Sciberc, it would undoubtedly feel more natural for a Frenchman to put the adjective after the noun as this happens so often in French.

But if he wants to speak Esperanto well he must adopt different habits, as the overwhelmingly customary order in Esperanto is adjective first.

Of course, there are cases when it is better style to put the adjective after the noun or even cases where there is no choice (see below), but this doesn't invalidate that the normal order is adjective first.

Mi deziras al vi ĉion bonan.
.. tabakplantoj kun enkondukita geno respondeca pri la kovraĵa proteino ..
Mi farbis la pordon ruĝa.
.. montris, ke la samspeca oleo vendita en Katalunio ..

My normal statement to beginners is something like "Esperanto has a flexible word order but in most cases there is also a 'most common' word order. In this case, it is most common to put the adjective before the noun, unless you want to add a special emphasis or to make something clear that would otherwise be confusing. I don't want to trample your creativity, so you can feel free to order your adjectives and nouns as you like, but you should be aware that putting the adjective after the noun isn't the usual choice, and people might assume that you are trying to add special emphasis if you do it"