Apologies if asked but searched and couldn't find a specific response.

I'm currently on 49 eligible flights so going to hit Silver on my next trip (EDI-LON return). #50 will be EDI-LON in the AM with #51 the return leg in the evening.

Will I turn Silver between flights and be able to use the benefits (mainly thinking about using the lounge at LHR that evening!) or will I have to wait a couple of days for it to credit and show my new status before I can use it?

Thanks