What's important is after you get the first N customers, the way you acquire customers will likely change. You'll exhaust your personal network eventually. Knowing your Ideal Customer Profile (ICP) is important and so is having a good understanding that the value/price of your product dictates what kind of sales/marketing you can do.
Things like cold emailing are fine for your first few customer development calls, but generally if your deal size is less than $1-2,000/year then (with exceptions) you should stop doing this after you get the first customers.
I run a low price point SaaS for SMEs (avg price is <$100/month), so this required switching from just messaging people I knew, to getting SEO, word of mouth, and the viral loop working. Outbound/inbound sales is not economical at that price point.