>>> I have wrapped the bag with plastic with the hydrator 3.3 so it can soak in, and will do the same with the fatliquor. Is this right?

Here is the instruction that is copy and paste from the above post:

Instruction . . .
1- Apply Fatliquor-5.0 and spread for an even appearance until fully saturated.
2- Before the leather is completely dry or about 25% moisture level more is applied until saturated again.
3- When dry to normal used the leather moisture content may be read with a leather moisture meter or an equivalent wood moisture meter to about 14%.

Instruction does not mentioned to "wrapped the bag with plastic".
Reason:
All water content from the Hydrator-3.3 and Fatliquor-5.0 has to eventually evaporates only leaving the fat and oil content that only benefits the leather when dry.


>>> and do i have to warm-up the fatliquor

A warmer 20 to 50 C fatliquor increases penetration and evaporation of the spend water content.


>>> and how?

Warm it up from a bowl of running hat tap water, suffice.