TL:DR

I understand how your feeling and a bet a lot of other UK applicants like myself are also feeling this. Considering with the old paper based application you got that confirmation that we seem to be missing with this years online application.

I can only offer my two bits, firstly I checked back a few times on deadline day to see if they added a submit or complete button because I applied within a day or two of applications becoming open so they might of added one since I applied (me being paranoid) but nothing was added. Tbh I think this is the reason why I feel like how you mentioned because there is no sense of it being complete without that final “yes” so to say.

What helped me was rereading the email you get after completing the application part, the one with your web ID you get before uploading documents, as it says on there;

“The UK JET Programme Office will not be able to confirm receipt of documents over phone or email. The online portal will indicate your uploading status after you upload your documents.”

So the way I see it is that as long as you have uploaded all the documents that are relevant to you that this same email asks for with the table at the bottom you are done and just have to wait for the email with if you are invited to an interview or not.

My guess is that we will hear end of Jan early Feb as timeline online says this year interviews are Feb/March, if they are not delayed due to arranging them to be online as someone else posted.