Esperando Que vs. A Que

[Bobbert]

I can't find a rule and I’m unsure if I'm hearing "que" or "a que" in sentences like:

I'm waiting for the bus to come
Estoy esperando que/a que venga el camión/autobús

I'm waiting for my friend to come
Estoy esperando que/a que venga mi amigo

I have been waiting for you to bring me a coat
He estado esperando que/a que me traigas un abrigo

I would appreciate it if someone would give me a rule and/or clear up what I’m hearing or not hearing correctly.