Safe to introduce?

[merecat]

I'm currently fostering a 12-week old kitten whose had her health check (and was cleared), but her vaccination is scheduled for another week or so.

Would it be safe to introduce her to my resident 8 month old? 

ETA: She was found in a cardboard box in a street, and was quite scrawny. 

 

[GoldyCat]

Was she tested for FIV and FeLV? Were the tests negative? Has your resident cat been vaccinated? If the answer to all 3 questions is "yes" it should be safe to introduce them.

 

[merecat]

Yes, thanks!

The resident kitten hasn't shown any signs of aggression, but loves to follow her around and observe her. Sometimes he'll attempt to pounce on her back.

The foster kitten has gone from hissing whenever she sees him, to mostly going about her kitten business.

How can I tell when it's time to separate them?