Can HIV incubate within hours and start showing flu symptoms in 2 days?

No. Hiv is a virus that diminishes and significantly reduces you immune system specifically the t line. Influenza is a virus that incubates for about a week sometimes less and causes a powerful respiratory infection. If this is what happened you are more likely to have flu than hiv. Most with HIV begin to have " opportunistic" infections like thrush which is fungal and normally suppressed.