Sounds really exciting, and a big challenge! Your in the right place for some great resources and a community of people who could help, also stuff over at https://testautomationu.applitools.com/.
Advice for me is always best context based on things like budget, experience, tech used in house, current delivery methodology, desired future state etc so hard personally to give any specific advice.
Maybe start with really clarifying (if you haven’t already?) why your company wants to start testing / what caused them to hire you for that role, understanding particular risks, concerns, regulatory requirements, standards to hit (ISOxxx) or current issues impacting customers and building tests around those areas first?
Great to see start-ups hiring QA’s!!