@Desiree Board For your mix of long-term rentals (LTRs), short-term rentals (STRs), and house flipping, an LLC is ideal for liability protection and pass-through taxation.

For reasons I don't yet understand, if the property is sold I cannot take advantage of a 1031 Exchange and my gains will be taxed as income, which will be 35% federal and 11.3% CA income tax. At

Please consult with an accountant specializing in real estate taxation. 

Are there times of the year I should invest in, such as first Quarter? 

@Drake BackmanBigger Pockets is a great place to find a tax strategist specializing in real estate taxation.A good real estate tax strategist can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding a tax  strategist specializing in real estate taxation, business taxation, financial planning and tax planning.Consider working with your tax strategist remotely to expand your options.I would also recommend looking for a tax strategist willing to work with you throughout the year.

Usually quarterly.  

Things like this are why it's important to work with a professional who is well versed in real estate taxation because the "common/simple" strategies taught frequently like BRRR or house hacking actually get fairly complicated when it comes to handling it correctly. 

@Marko BukvaI'm not entirely clear on the plan and ownership, but there are potentially several different types of tax at play for a transaction like you're discussing - gift taxes, estate tax, income tax, property tax, documentary transfer tax, etc. 

I opened an  partnership LLC, and I am learning now about taxation it will be treated as a dealer and not as an investment.

A good real estate accountant can save them thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend that they find a tax accountant who specializes in real estate taxation, business taxation, financial planning and tax planning.I would also recommend that they look for a accountant willing to work with them throughout the year, who can help them strategize and who is responsive when they want to know the consequences of the financial decisions they are making throughout the year.Good luck.