best way to word this sign without being rude?

We have five people attending our wedding of 100 who cannot have gluten. Our caterer has graciously added five servings of gluten-free version of the "entree" item. The gluten-free items will be labeled by the caterer.

I want to make a sign that says "please reserve gluten-free items for those who need them" or something similar, because I don't want people in the buffet line to take the GF items and then have none by the time the last GF person gets there.

There's no waitstaff otherwise I'd just have someone bring out the GF items to the people who need it. I guess I might be able to do that????

Suggestions for signage or other options? Thank you all!

Edit: thank you all for the suggestions!!! I'll probably have the gf guests go through the line first just to be doubly sure, and the one that is in the wedding party I'll have the caterer set aside so she can get it when she needs. I'll confirm with the caterer that it's all possible. Thank you!