Filing Visa application (Outside of UK) after course start date but before last enrollment date

Hi, I am applying for a student visa for my master's in UK from India. Usual visa processing time is 15 working days and if applied using Priority method, the visa processing time is 5 working days.

I haven't still received my CAS yet but looks like I will receive my CAS on or around 6th or 7th January.

However, my Course start date mentioned is 7th January (as i understand from my prospectus and university representatives) and my last enrollment date mentioned in CAS is likely to be 22nd January.

Now the question, can I apply for my visa after course start date e.g., on 9th January using priority service (usually decision in 5 working days), is it likely to result in any negative impact on my application?
Thanks