Alas, your report is difficult to decipher.
I deduce - perhaps wrongly - that you have some applications configured (where/how?) to auto-start in background when Plasma launches, but instead they start with their normal GUI window.

1. Can you say how you configure Plasma to auto-start the applications in question?
2. "it usually opens in a full window"
What does? The auto-started application?
3. You imply that "Clementine and qBittorrent [should] run in the background. And that's how it's set up". Where/how have you defined that they should?
4. "I have two conky scripts, of which he hectic starts both or just one. Although I only call a bash command in which things are collected."
I am afraid this is totally unclear. And what bearing does it have on the problem you are reporting? Where would the suggested 'sleep' occur?

CC: (none) => lewyssmith

OK. KDE System Preferences/Startup and Shutdown/Autostart. Here, under applications, I loaded two programs. Clementine and qbittorrent.
The computer will restart and the two mentioned programs will appear on the screen. Although it shouldn't appear, it should run in the background.
It is also possible to specify a script for the automatic start.
here is a bash script given.
which reads:
#!/bin/bash

# check run conky
if pidof conky | grep [0-9] > /dev/null; then
     killall conky
fi

path1="${HOME}"/.conky/my-system
path2="${HOME}"/.conky/openWeatherMap

conky -bc "${path2}"/ow_All.lua &
conky -bc "${path1}"/all_info.lua &
exit 0

Two conky collected.

oh yeah Sometimes one of the two conky scripts does not load.

Thanks for the clarifications.
> the two mentioned programs will appear on the screen.
> Although it shouldn't appear, it should run in the background.
So we agree that the problem is that the two applications start with a GUI rather than in background [Systray?] as you wish.
How do you configure *that*? In the same place as you describe in comment 2? (I am not under Plasma at the moment, but can look if necessary).

Did it work as you want under Mageia 8?

I have just started Clementine from the menu, and see that it goes directly to Systray, no immediate GUI. From a terminal, it is not consistent about [not] showing its GUI window, sometimes does, sometimes does not; but always goes to Systray.

For qbittorrent I cannot make it start - menu or command - without showing its GUI. It puts itself also in Systray, and when you close the GUI window with its 'X', stays in Systray (which can be configured).

In Mageia 8 there was no problem with these.

The problem is that the programs appear in Hungarian for me, and I don't know the exact English names.
I could take a screenshot, but they are also in Hungarian.

Clementine should have something like this
Tools/Settings/Behavior
Always hide the main window when Clementine starts.

qbittorrent is almost the same
Tools/Settings/Behavior
Desktop/Start qbittorrent on the tray

(In reply to Mészáros Csaba from comment #5)
> In Mageia 8 there was no problem with these.
> 
> The problem is that the programs appear in Hungarian for me, and I don't
> know the exact English names.
In terminal you can tell program to pick non-system language using LANG environment variable
e.g.
LANG=C clementine
or
LANG=en_US clementine

---

I guess this discussion rather belongs to forums than bug-trackers.

CC: (none) => altsyde

I will try to reproduce this; I think you have given enough details.

(In reply to Lewis Smith from comment #7)
> I will try to reproduce this; I think you have given enough details.

daviddavid told me years ago that we can assign bugs against plasma to kde team, without first investigating further,

Assigning to them now.

Assignee: bugsquad => kde
CC: (none) => marja11

Could you report this issue upstream at https://bugs.kde.org/, please?

CC: (none) => geiger.david68210