This is mostly my opinion. I think describing EC as going into panic mode is a bit exaggerated.
Although there has never been an exact time stated as to when EC left Henry's Tavern, EC stated about an hour after KJ & B came by Henry's to say, Hi, I'm walking the dog, then headed home.
IMO it took less than 5 minutes for EC to ride home from HT (most of the ride downhill & then flat).
EC expected KJ & B to be home.
EC most likely was concerned to find them not home, I speculate.
EC became worried when KJ didn't answer calls or texts. She stated in her interview w/Channel46 news, she called a bunch of times & texted w/no answer. She thought maybe KJ had lost or dropped her phone w/o realizing it. EC stated that KJ always answered. Then EC stated she tried the 'find my phone' app & saw the phone was in PP & not moving. So she 'got back on her bike & headed for the park', as stated by Karyn Greer w/11alive news. The bike ride to PP probably took about 5-9 minutes depending on where EC entered (at 10th & CA or 12th & Piedmont Ave). I speculate EC entered at 10th & CA because she stated in several interviews she saw Bowie right away (that ride would have been flat, then mostly downhill).
So based on speculation, I would say EC got home about 12:40am, left apt around 12:52am, arrived at PP around 12:59am & called 911 at 1:10am.
JMOO
So, using your timeline, it was less than 15 minutes between the time EC got home and the time she left the apartment. You don't think it's a little weird to use Find my iPhone that quickly? To find a grown woman? You wouldn't try contacting anyone else first? Waiting a little longer? Maybe looking to see if KJ left a note saying she'd gone somewhere? If I was trying to locate my teenager who was out past curfew or super-late getting home from work, I might go right to FMI, but it seems like an overreaction to use when you want to locate a grown woman who works in and has friends in the neighborhood. JMO.