Throughout the construction process, things happen!  Delays happen, material gets backordered, product can get discontinued and mistakes happen.  Houses are built and renovated by hand and there are a lot of people included in the process. Don't expect everything to go 100% - there will be pivot points throughout your project.  But that's okay!  If you understand what can come up, you'll be better prepared when it does.  Through team work and trust, you and your builder will get through the bumps (regardless of how big), just fine!