Usually arbitrators answer in 24 hours after the arbitration is opened.
However, due to the running scam events, see URGENT: Certain banks banned until further notice, arbitrators are more busy than usually, and there may be more delay.
Also, are you doing a fiat trade or an altcoin trade ? If you’re doing a fiat trade from a bank used by the scammer, your counter-party may be afraid of that and reluctant to release its BTC.
What’s the onion of your arbitrator for this trade ?