Syag advice is correct and also Nechomah’s advice.
This is what I do. When you put the fresh yeast in a bowl with a teaspoon of sugar for every ounce used from the full amount of sugar used in recipe, sprinkle some of the flour on top of the yeast mixture, so that it will foam. After I’ve finished kneading the dough, I put the dough in a well greased (with margerine that has been frozen – to use less)very big stainless steel bowl. Put a few drops of canola oil smeared on top of the dough by hand or with a silicone brush – whatever is easier. Cover with saran wrap. Then put in to an 50 degree C preheated oven, on the bottom shelf. After a half hour, knead the dough in the bowl again for a few minutes, then cover again with the saran wrap and then leave in the oven again for another half hour. I then take out of the oven, remove the saran wrap and cover with a clean tea cloth. Preheat the oven to 170 degree C fan. I leave the dough to come back to room temperature covered for about another hour, in the bowl. Take out of bowl on a lighly floured surface. Plait the dough as you wish. (I do 6 strands). Then I place on a silicone baking sheet in a aluminum baking pan (jelly roll pan), egg wash and sprinkle with sesame seeds. Place in preheated oven straight away and bake until done.
Be matzliach!