"What kind of start and finish time would be bad?"
Of course, that varies with personal opinion. Here's a couple of gems.
FR 0891 757 LAS (18)01:26 PHX (19)02:33[ 0:45] 1:07
FR 0891 757 PHX (20)03:18 DFW (00)05:27[ 3:09] 2:09
FR 0892 757 DFW (03)08:36 PHX (03)10:41[ 0:45] 2:05
FR 0892 757 PHX (04)11:26 LAS (05)12:23 0:57
TU 6009 757 YVR (17)00:53 BFI (18)01:41[ 0:55] 0:48
TU 6009 757 BFI (19)02:36 RFD (00)05:51[ 2:19] 3:15 C
TU 0490 757 RFD (03)08:10 LAN (04)08:58 0:48
FR 0897 757 RNO (19)02:52 MHR (20)03:34[ 0:46] 0:42
FR 0897 757 MHR (21)04:20 ONT (22)05:34[ 3:26] 1:14
FR 0834 757 ONT (02)09:00 SLC (04)10:27[ 0:45] 1:27
FR 0834 757 SLC (05)11:12 BOI (06)12:07 0:55 4:18
To be honest, they changed up the YVR pairings to end in LAN instead of IAH, which makes it better. The LAS deal is a ball buster, if you ask me. These are considered the worst pairings in the domicle. As such, they will tend to go junior. A lot also depends on how "clean" the line is. If there are no two day filler (stuffers to bring up line credit) trips in the middle of your week off, bad pairings become more senior. Some easy flying might have four shows in 28 days, and thus be more junior. You have to look at line quality based on how a commuter would see it. That's pretty much how things work as many local guys will often bid reserve and the most commutable lines are senior.
"would it be better for a newbie to bid reserve"
It would during times when the reserves don't work as hard, which (I'm guessing here) is most of the time. Also, bidding reserve only makes sense if you live in SoCal.
As a parting comment, ONT hot standby has historically been really junior. You show around 5pm and are done at 1am. You sit around ops and wait for an airplane to break somewhere. Internet access, lounge chairs, and a TV. They don't use you much and you get the same number of days off as a lineholder. Bad part is you have to show up instead of just being on call, like a reserve. Good part is more hard days off than a reserve and they don't actually make you fly much.