I can't speak for my husband sucking a bbc because we are still looking, but my husband has sucked his young nephew getting him hard to fuck me.
I'm sure he won't have any problem sucking a Black cock to get it ready for you when the time cums!
Once a white cuckold has sucked his first cock to get it hard for his Wife, sucking others isn't a problem.
In fact, he is probably looking forward to sucking your first Black lover hard for you and licking your creamy cunt clean afterward as well.