Flower Center Pieces

I think all of your ideas are valid. You can mix real and fake (fake looks better with fake IMO) and get them the day before. Just make sure you call ahead and have your order down to a T, that way your chances of something happening the day before your wedding is minimal!

I was MOH for a wedding last year and we made all of the brides centerpieces from fake flowers @ Michaels/Hobby Lobby. Looked great!

We did DIY fresh flower table arrangements! I ordered flowers from fiftyflowers.com that were delivered about 2-3 days before the wedding and arranged them in bud vases (very similar to your photos - a couple flowers and some greenery per vase) the day before the wedding. Biggest recommendations / lessons learned is to store them in your fridge both before and after arranging them to keep them fresh and to choose hearty flowers - I used ranunculus and the stems were very fragile and the petals didn't look too great by the the time reception rolled around.

A lot of the time, mixing fake flowers with real ones highlights which ones are fake, whereas having the entire arrangement done with fake flowers can make them look more real and give the arrangement a more uniform look.

My 2 cents is that it's a lot less stressful doing arrangements with fake flowers that you can do ahead of time vs having to wait until the day or so before the wedding to make arrangements with real flowers. You're the best judge on how you'd be able to handle that situation and how much you'd want to use real flowers vs fake ones, so do whatever is best for you