Baby blocked nose

Hi all, baby, 2weeks old, has blocked nose when sleeping in air-con room. Used Sterimar and sucked out with nasal aspirator (lollababy and tollyjoy), but no mucus sucked out. Question: how long do you press on the Sterimar per application? I usually press it for 0.5-1s as I'm afraid too much water blow into his nose. The block nose seems to be affecting baby's sleep as he keeps waking up from the congestion. Any advices?