The most honest answer to this question is also the most useless: you need funding when you need it! There is no good answer to this question, because it wholly depends on the founding team's financial circumstances. You might not have personal capital to contribute to your venture, and that's okay! But all forms of external capital come with tradeoffs (even grants, you will spend many hours writing them!) so it's a good idea that you make as much possible progress on your venture that you can before seeking capital.