Tried, most of apps work well with am start but there is one which I'm currently working on failed.
The interesting thing is if I clicked that app icon manually to launch it then click BACK key to exit, I then can use am start launch it successfully. That's why I'm searching a way to finish the "preparation" steps.
Now I can do it with a third party component named "AndroidViewClient" in Python by writing:
import re
import time
from com.dtmilano.android.viewclient import ViewClient
device, serialno = ViewClient.connectToDeviceOrExit()
vc = ViewClient(device, serialno)
apps_tab = vc.findViewWithContentDescriptionOrRaise(re.compile('Apps'))
apps_tab.touch()
time.sleep(5)
Problem solved!