Is this an on time application ? Please help

Hi guys,
My visa was expiring on the 18th of june2016 and my lawyer just filled in all my application and had it sent out by post on the 16th (thursday). I just tracked the post and it says that the parcel had been delivered or recieved on the 17th (friday) however I have not got any confirmation from the home office themselves.. And considering today is sat and tomorrow Sunday, I would get a confirmation on Monday or later which is the 20th onwards.. So is my application considered in time or have I overstayed....

Also my wife has been working at her current job for the past 3 years and we have shown a joined income with all her 12 month salary.. now she has got a new job offer with obviously better pay.. So can she change the job considering that I have already submitted my application or is it must for her to keep working at the same job till I get my visa ? Thanks

If you submitted an application by post before your visa expires, the date of posting is considered the date of application.

Suggest your spouse waits till you get your visa as HO might want to confirm her income and employment.