My suggestion would be to start with small numbers of deer. That being said, I would go ahead and plan on having one or two empty pens to begin with. That will allow you to grow easily and also help if you need to separate deer for whatever reason. I do not own my own deer, I work for a guy and manage close to 200 deer (in breeder pens). When I first started the herd was around 75. Being two years in I have learned several things the hard way, though I had a great contact list to help with small problems. I genuinely wish that I could have started with very few deer to learn slowly. It is a great job to have none the less. One more big piece of advise is to visit as many farms as you can, and get as many phone numbers as you can. Other than that have fun and enjoy the animals!