As much as you need to build out the product and raise at a 3-4x increased valuation.
Typically that's 500K-1.5M and gives you 1.5-2 years of runway to build product, customers and team.
I've answered this question in different forms many times on Clarity. I'd encourage you to either use the search feature and search for Fundraising and/or "seed" or click on my profile and look under the answers tab to get the answer you need.
If you have further questions after reviewing what I and others have written, I'd be happy to help via a call.