I was meaning 20inches, not cm
I know i should start with smaller, but i did take a workshop about darkroom and the printing was my point of taking it, we practiced on 8x10 papers, but for the last days we have been asked to print at larger size [not sure if 12x18 or 16x20] for an exhibition, so i printed about 3 larger sizes prints for that exhib, so i am planning to play with something larger than 8x10 anyway myself, and i feel if i can gat trays that are about 20in or larger then i can print any size from 8x10 up to larger so i don't need to be many trays again due to getting different print sizes, the bigger will handle the smaller, but small i will be limited to its size until i can afford bigger trays sizes, i am already started of printing and i know the concept of it, so if i will do it at home myself i think i don't want to do 8x10 all the time and i am sure i will do that 8x10 in less than week and then i want bigger, and i can't wait weeks to order another trays and waiting and bigger papers, i go with larger directly is safer for me than going with smaller then larger.