As the attacker punches, block and step through with a deep step,  your advancing foot will be almost level with their rear foot. Turn through 180° while gripping under their rear armpit or by the belt if you are shorter than them. Using this hand, draw the attackers balance forward, but not so they are bent over. When he’s on the verge of falling, bring your leg up and backwards into his stomach, while continuing to draw him forwards — he should wheel about your leg.

The Wheels are used in different circumstances depending on your position/step through:

koshi-guruma – if your feet end up between the attacker’s feet

ashi-guruma – if you step through a little further

uchi-mata- if your feet end up either side of his rear foot

o-guruma – if you pass his feet  So even if you can’t do the throw you originally planned because you’ve stepped through too far, there’s always an alternative throw you can do instead.