As nice and convenient as the follow to join option may sound, I would be very careful with opting for it at this stage if I was in your shoes, especially considering that your NL should be arriving any time soon. If you hadn't already sent in your papers and KCC was yet to process them, it could have been a viable option to pursue since you're fortunate to have a low CN. Follow to join is a very stressful option for a time sensitive application such as a DV lottery visa.
If that is an option you want to explore, you will need to notify KCC of this change. You can't just show up alone for your interview and now tell them your wife will be doing follow to join. Be aware that you may need to do a lot of follow ups following your own interview to ensure your file gets sent back to Nigeria if you do follow to join, and there's no telling how long it might take before the file get's sent or when your wife gets scheduled for an interview in Nigeria.
My suggestion to you would be to proceed as planned, get your wife to join you in Germany for the interview (or where you the one flying down to Nigeria for the interview)? Anyway, proceed as planned and attend the interview together. Following a successful interview, come into the US together to activate your LPR status, apply for a re-entry permit (wait and do the biometric for the re-entry permit) then she can go back to Nigeria and work for this employer for upto 2 years without jeopardizing her LPR status. Of course you don't have to do follow this suggestion, but this is what I would do if I was in your shoes.