Most secondary questions aren't going to be asking you about shadowing hours. That's more of the primary application question. Secondary questions are going to ask you specifically why you want to be an osteopath and why you think you are a good fit for their specific school. If you are wanting to include in your secondary your current activities or write about how you are familiar with osteopathic medicine, I would wait until you shadow a DO. Your writing will come from experience. If you are bull sh*tting, they will probably be able to tell. It's still very very early to send in primary apps, let alone secondaries. I didn't know they sent out secondaries this early. Didn't the primary apps just open up in early june?
I guess my main point is, there's no reason to include what you did/felt/saw during shadowing in your secondary unless you were inspired by something by something or learned something new. Since you haven't shadowed yet, that either means that what you are wanting to include in your secondary is pointless information, or you will be writing about what you think might happen in the future. My advice would be to either wait until you shadow a DO. If you can write a secondary about a shadowing experience that hasn't happened yet, it probably shouldn't be in your app in the first place.