Yes—you can usually use a prepaid Vodafone number right away for most registrations. Just don’t assume it will work for everything: some government and bank steps require reliable SMS delivery and, in some cases, phone verification tied to your ID or a Spanish bank setup.
In our case, we started with prepaid sim we bought at the airport, then moved to Lowi and converted to regular mobile lines for me and my wife. Later, we switched again to Vodafone and got four lines (we’re a family of four). Our plan also includes internet/cable, plus Prime and Netflix, and we pay €70/month.
The good part: we didn’t have to change our original number throughout the process.