Is there any way to rough capacity plan, production plan or schedule before BOMs are maintained?

I think the answer is no, but I want to hear from you all.

For Rough Cut Capacity Planning (RCCP), you'll only need to plan the critical operations. So, for orders of completely new manufactured product, you can make a mock up routing containing ONLY the critical operations, generate Bill of Critical Capacities (BCC) from it, and run RCCP. What do you think?
Rgds,
Paul