Welcome to the forum Piao Liang.
Your first picture shows that your plants have not been getting enough light. This means they have elongated and it could slow down your new leaf regeneration process. If you water after one or some have dried up the old leaves, you will cause the others to swell their old leaves.
I would give them as much sunlight as possible and then, when some have their old leaves dry, I would re-pot them so that you can water the individual ones with dry leaves and leave the rest dry until the old leaves dry up.
If you want to keep them in the same pots then I would not water until most have dried the old leaves.
Hope this helps.
Last edited by Allan1
on Sun Mar 22, 2015 11:36 pm, edited 1 time in total.
Lithops,Cacti,Conophytums,Tylecodons,Sempervivums and Sedums