Let it rise for 60 to 90 minutes, covered, at 22-24 °C (72-75 °F). It only grows by 30-40%. Go by volume, not the clock: the cinnamon can make it take a little longer.
Divide into 8 pieces of about 105 g (3¾ oz) and shape each into a ball. Flatten each piece into a disc, fold the edges into the center several times, turning the dough as you go, until the surface feels tight, then turn it over with the folds underneath. Let them rest, covered, for 15 minutes.
Seal the base. Fold again, pressing firmly, and close the underside with small pinches until there are no cracks or creases left. A well-sealed base is what keeps the ball from splitting in the water.
Oil the twine. Run the 8 pieces of twine, 80 cm (32 in) each, through your fingers with 10 g (2 tsp) of oil. This stops them sticking to the crust in the oven.
Tie each ball into 8 sections. Center the twine on top of the ball, bring it down the sides and cross it underneath. Turn the ball 90° and cross again: you'll have 4 sections. Repeat, turning 45°, to get 8, then bring both ends back up to the top.
Tie it on top, without pulling it tight. The dough is going to grow, and tight twine cuts into it.