Hold off on the CPU for now. If you want though you can start assembling the build starting with the Case & PSU. Using the Motherboard as a guide you can start doing some cable management and plan the build out but don't actually install it into the case yet. If you have a M.2 SSD you can install that onto the motherboard without having to worry about it later. You might be able to put the Memory into the system but it depends on your CPU cooler.
As long as it doesn't seem like anything will get in the way of installation, hypothetically, yes, but I'd just be patient and wait for the CPU, as it will simplify the process.
Hold off on the CPU for now. If you want though you can start assembling the build starting with the Case & PSU. Using the Motherboard as a guide you can start doing some cable management and plan the build out but don't actually install it into the case yet. If you have a M.2 SSD you can install that onto the motherboard without having to worry about it later. You might be able to put the Memory into the system but it depends on your CPU cooler.