It really varies on the project and the rest of your workload, but working linearly, here is the rule of thumb I use:
design research: 4-5 weeks depending on complexity
research synthesis and cross disciplinary workshop: 1-2 weeks
initial concept archetype exploration with down select session: 2-3 weeks
product concept sketching: 2 weeks
concept refinement: 2 weeks
design CAD: depends on how complex and how much internals have being worked in parallel
final design model production: 4-5 weeks
design revisions and CMF: 2 weeks
design for production: this can be long depending on where engineering is in the process but ideally 3-4 weeks
design oversight of NPD: until MP1 (typically 12 months)
Obviously other things can be done in parallel. The most intense time being up front from research to CMF documentation. Call that 3-4 months.