A few years ago I fitted some Uniroyal tyres and they took well over 1000miles to bed in. Felt like driving on ball bearings at first, then gradually settled in to a good grip.
Tyres do take longer to wear and bed in at this time of year. Cold / wet all affects the grip.
Give a bit longer.
Did you get a 4 wheel tracking check done at the same time as fitting? If not, may well be worth doing.