The deadline and when to send the documents

I am applying for the year 20-21 and I am soon about to send my documents, although there are some delays with receiving some documents from my country due to Covid.

Does that mean that if I will send the application before 22nd this will still count as me fitting into the deadline? Meaning even if it will be sent on the i.e. 20th, but it won't be received by 22nd but 23/24th due to some unpredicted delays, does that mean I still applied on the 20th sending the letter or is it necessary for SFE to receive the papers and process it by 22nd?

Hope this makes sense.

Thanks!