Initial state of SN74AUP2G80 dual FF
You should never assume any particular startup state for anything unless the datasheet provides specifics.

If startup state is important you need to include some sort of power up initialization sequence.  There are SUPERVISOR integrated circuits that reliably produce a delayed reset pulse on power up that can serve this purpose, like tlv803m (link to pdf).

That said, often a clock tick or two without any special handling might serve to get you to a predicatable state without problems.  You should think about how detrimental a few unpredictable states at startup would be to determine if you need to go out of your way here.