Seems to be defined by the learner goal and the market.

You can read a book and multiple books, but unless you are out there doing it (I.e. getting bids and getting contractors to truly get you an exact estimate) you will be far off from the numbers you want and may even lose money on the flip/rehab.The best advice I would suggest in my experience is that you should get into the line of work by either partnering with someone or working with someone on some projects prior to going into a flip on your own.

What is your financial goals and timeline to reach them?  

Once you're ready, create a goal (e.g., "I will buy at least one single-family home, duplex, triplex, or fourplex before the end of 2019") and then do it.

Building a network here can open doors to partnerships, mentorships, and local insights.3.Explore the Blogs and Podcasts: BiggerPockets has tons of content—blogs, podcasts, webinars—that cover everything from beginner strategies to advanced investment tactics.4.Utilize the Deal Analysis Tools: If you’re considering an investment, the deal analysis calculators are invaluable for running numbers and understanding potential returns.5.Set Clear Goals: Define what you want to achieve, whether it’s learning a specific strategy or connecting with certain types of investors.

Each project cost is around the 400k market without land cost.

check to see if there is still 179 on airplanes.. and then put it in the rental fleet at a very good FBO and then use it when you want to visit your new holdings your 1031 into.. buy RV's and put them in rental fleets.most syndicated RE projects these days will have some tax benefits.. just musing here.. 

I've done my projects solo so far and it has worked out for me, however, it is time consuming and not in the position to invest all into one deal.

Each option has different implications, so choose based on your financial goals.

It would be a rare new RE investor that could hope to have taken on this project without partners with experience.My point is investors in different stages of life and experience have different criteria for their RE investments.