its hard to establish KPIs with little historical data, what tips have you got for getting around this or refocusing kpis?

You have to start somewhere! I recommend setting a KPI for a limited period (month/quarter) to 'Create a benchmark for X KPI'. This ensures the expectation is clear that you are starting at square 1. And from that period forward you can use that measure as a benchmark and continue to improve as you gather more data over time.

It is definitely a challenge to set KPIs without having a good understanding of how your team has performed historically. In this case, I would look for industry benchmarks to get an understanding of where your team's should be. Consult other PMMs in your network or PMM communities (like Sharebird) for information.