Can you please tell me if it is preferable on Shavuos day to have cheesecake made of primarily cheese – very thin crust to hold cake together thus requiring shehakol? – after kiddush, then a few minutes later wash/hamotzi for a meat meal? Is it better to eat the cheesecake along with other actual mezonos, then wash for the seuda?
In most instances the cheese cake is going to be mezonos. If it is baked the mezonos part becomes the ikkar (main part), and even if it isn’t baked, it will still be mezonos because you also want the crust for its taste. (If it isn’t baked, it is controversial if it will be two brachos or just mezonos.) The only case that you will only say shehakol is if the crust is very thin and not tasty, and only there to hold the cheese.
Getting to your question it is better to eat the cheesecake along with some mezonos. The reason is because of “Kiddush bmakom seudah” – that we have to eat the meal in the same place and right after saying Kiddush. In your question you write that you will be eating the meal a few minutes later. Although b’dieved you would still be yotza Kiddush b’mkom seudah however it isn’t l’chatchila. Therefore it would be better for you to eat actual mezonos, this way you will have kiddush b’makom seuda, even if you wait.
One other point, when eating cheese cake, regarding a bracha achrona and for Kiddush bmakom seuda, make sure that you eat a kzayis of “cake”, “ bkday achilas pras” within approx. 4 minutes (you can be maikel up until 9 minutes). You can’t include the cheese for the kzayis.
Sharei Habracha 15-30, O:CH 273-3,5 , Oruch Hashulchan 202 -10, Minchas Shlomo1-91 ftnt 4, Sharei Habracha 14-14..