Is it permissible to perform ghusl with the intention of removing janabah resulting from a wet dream upon waking, even if one does not see any fluid until much later, in order to avoid performing ghusl outside the home and the embarrassment or missing of lectures that might entail?

If you experience a wet dream but do not find any semen, you are not required to perform ghusl, by consensus, because ghusl is not valid before its cause occurs. And if semen is discharged after a long period without desire, it does not necessitate ghusl according to the majority of scholars. If the fluid is not semen, it does not necessitate ghusl at all.