Ask HN: How to shape company seed stage "culture"?

I've worked and lived with my cofounder for almost 5 years now. In March we brought on another guy. Culture here so far is very loose without a set regiment. We try to do a status update everyday in a 10 to 15 minute standup meeting but that's all. We're about to make a few more hires both in engineering and marketing (bringing it from 3 people to 6 people on the team). How do I shape culture of the team? I see a the Treehouse guys doing 4 day weeks, the Stripe guys throwing dream machines at their devs but I don't think we can afford some of those perks.