SWOT analysis for a startup in the initial days may give results that are likely to be discouraging.The reason for saying so is that like a growing baby the strengths of the organization still require time to mature. Also the weakness and threats will seem larger (depending on the competition) at earlier stage. So only Opportunities are the driving factor and those opportunities were the trigger for starting up too. the situation does not change that much in the early days of the business
However in Lieu of SWOT analysis, I will suggest PEST analysis that will help you focus more on defining the target market and customer segments.