vodafone speed on change of plan

hi

have just changed from Vodafone 200 / 20 to 950 / 450 which seems to have kicked in this morning however the downloads have stayed the same or a bit less while the upload has improved.

im not really worried about upload but just wanted to know if it takes a while for download speed to learn and change overtime as some comments have said around the place

not a concern, just more curious at this time