You need to get the jack and blocks out from under the bucket. I see you have the pin removed from the left side bracket, I assume you have the right side also? If so you need to rig up some way to hold the front of the loader up from the top of the bucket or from under the cross tube so you can remove the blocks. Once the blocks and jack are out o& the way you can start lowering the bucket and arms , once the support legs touch the bucket should still be a few inches from the concrete, at this point the bucket weight will be gain to tilt the loader up and out of the rear supports the further itç—´ let down until the bucket rests flat on the concrete.
Also just noticed the kickstand legs are in the lowest holes, move them to the higher ones , this will give you more lift on the rear brackets as the bucket sets down.