Just to say, peat holds water, the last thing you want with clay. Use other amendment. And of course, you NEVER amend just the planting hole. Amend the entire area.

Also, something newbies don't understand: the smaller the tree, the faster it will grow. The larger the transplant, the longer it takes to re-establish roots and the slower it will grow. Tiny whip will outgrow a big transplant in 5 years time.

Have you had the soil tested? Camellias want acid soil and if yours is alkaline, amending with peat will probably not be enough for acid loving plants. You would be better off growing them in large containers or raised beds containing an ericaceous medium.

Pine fines can add some acidity and won't hold as much water as peat. Walmart used to sell generic bags fairly cheap. I haven't priced them lately though lol. Pine fines are also a good mulch for acid loving plants too.

Camellias are beautiful and long lived. You want to give them room. Try to think of the future 20 years from now. They can be moved when dormant in the cool months but ideally, you dont want to be digging them up because they were planted too close together. Better to pot them up in larger pots on ideal soil until you get their locations prepared rather than put them in smaller holes that are prepared with tjust ok soil. I like a potting mix I make myself. One part peat and one part pumice. Mix that together. Then add 1/4 of that volume in sand and 1/4 good garden soil. If its clay use the topmost part and break it up so no clods or stones or big roots. Then add some charcoal from a wood fire ---not the ashes just the charcoal bits washed clean with a hose. Maybe a shovel full or 2. Dont use a fertilizer in the mix or in the planting hole. Camellias dont want manure or anything too strong. They prefer a good mulch that breaks down over time. Something like oak leaf or redwood but any good weed free leaf mulch is nice. Keep it well away from the trunk. Let the roots be near the top and dont smother with too much soil. The roots should be near the top and then a light leafy cover to shade them and hold moisture in.

I have some on a gentle sloping area so they can not stand in water. Raised planting areas work very well. It has to drain wherever you are putting them. Think about them being small trees in 50 years. Kramers Supreme is a prettier red with more fragrance in early morning sun here. I moved that pot around for 5 years to get the best location. If youre not in a hurry you can try out different spots before you plant. No hot midday or afternoon sun! Late day slanted light is ok but dont let the plants get hit by harsh drying winds if you can help it. Filtered light under a tree is good. I have one by my front door that lost its protective tree. Every late spring-fall I have to put up a shade cloth to protect it from the direct hot sun. Off it comes when the sun gets lower in the sky and flowers beautifully into March. By early May the cover goes up again. So you can modify locations that are not ideal. The more soil you can replace with improved soil, the happier your plants will be. Keep the mulch on and water generously in the warm months. Camellias dont like drought at all.

I'm not sure about "They can be moved when dormant in the cool months " mentioned above. There's no observable dormant period in the SF area. Right now is the cool season and the camellias are blooming.