Not just yet
Definition 1 of 1
Pro Tip 1/3Time Delay
Indicates a small pause or delay will occur before something happens, suggesting patience. 
Can we leave? Not just yet, let's wait for the announcement.
Pro Tip 2/3Anticipation
Often used to keep expectations alive, implying that while something isn't happening now, it will soon. 
Will it start to rain? Not just yet, but the clouds are coming.
Pro Tip 3/3Polite Refusal
A softer, more polite way to say 'no' without completely dismissing the possibility. 
Are you selling your car? Not just yet, I'm still considering it.