Here’s a general timeline for I-bonds to help you:

If you buy I-bonds, you cannot withdraw the money for 1 year.

After 1 year you can withdraw your money, but you forfeit 3 months of earned interest.

After 5 years, you can withdraw the full amount without having to pay the 3 month interest penalty.

General info: the rate does change every 6 months to adjust for inflation. And each individual can only buy $10k in i-bonds per calendar year. There are some tricks to buying more beyond the $10k limit through tax returns, or through children, or an LLC (if you have those options) but hopefully someone more knowledgeable on that can comment more.