Seriously? It varies widely especially for rigs that have inexpensive CPUs like Celerons and some of the slower Pentium models. Even the i3-7100 takes longer than 60 seconds to complete the boot process and load the purposefully delayed start items.
Any i5, i7 or faster or Ryzen 1500+ should get there in under a minute, true. It also depends a lot on exactly what is installed on each rig, although if it is a true bare bones system without anything other than mining software added, it's probably fine unless it's a Celeron under 3.0GHz.
Overdriventool starts after 10 sek, miner starts 20 sec after logon.
4gb ram, pentium g4560. 13 amd gpu. Ssd.
No problem.
Yep, G4560 or 4600/4620 are hyperthreaded, therefore essentially twice as fast from a logical point of view. You should be fine!