The short and over-simplified answer is:
The longer more complex and realistic answer is "it depends on your projects".
I generally encourage junior designers to start applying once they have 1-2 good projects in their portfolio. See this notion page for tips on what makes a project good.
However, depending on the scope, complexity, length, timeframe, etc... of your best project (which should ALWAYS be first on your website portfolio), you might gain a lot of value from adding a few supplementary projects that fill in the gap.
For example, if your best project focuses mostly on the "implementation" and iteration steps of design after a set of clear goals and objectives have already been defined with research, then you might consider including a more "exploratory" project where you focus on research methods as your second one. Try to avoid having many projects that follow the exact same "formula" as it becomes rather redundant to the viewer of the portfolio.
This stays true for a 3rd or 4th project. Perhaps one you can focus more on the designs of a very specific feature and dive deep into explorations on micro-interactions and animation. Perhaps for another you can really emphasis your visual chops for less complex but beautiful work.
For all the projects after that, you can include it, but be aware that they might never really get clicked on unless they are very unique and appeal to a specific role.
One thing I want to make very clear though... This does not mean you should STOP after making 3 projects.