is it possible going to Victoria Peak in the morning then to Disneyland just before lunch?

Yes, you can do that, but you will use the rest of the day in the Disneyland.
From the Peak, you can walk to the Central Station to take the Tsuen Wan Line to Lai King Station and then change to the Tung Chung Line to get to Sunny Bay Station.
At Sunny Bay Station, you will find the Disneyland Resort Line to Disneyland directly.