invoke Skype (portable) only on demand ?

I would be using this program only infrequently, and do not like the behavior of installed Skype that it comes up ready to use in the Windows taskbar at every bootup -- in effect already ON and operational: I'd much rather invoke the program only at my discretion, like nearly all other apps. However, I do not notice any setting available in Skype to adjust this behavior.

For this reason, I have downloaded the portable version from here (but have not tried it yet), in the hopes that it would operate in this manner that I prefer. That would be consistent with the behavior of every other .PAF type app that I can think of, and I have quite a few of them here. Their footprint is close to nil, usually with no registry involvement, and Windows is generally not aware of the app at all, until you go to use it. In addition to being able to run the app on any PC off of an attached thumb drive, this is most often a major plus in my estimation.

I'm inquiring here, because I already have a Login here, and Skype forums might just respond with a "this is a portable version issue, take it up with them." I already see how the installed version works . . . .