So I have a '95 K1500 with a 5.7L and the 4l60e transmission.

If I don't drive my beater for a good month, and hop on it to get it to move forward, there is a slight delay. The truck won't immediately move forward after I shift it to "D". I have to wait a good 30 secs or so.

Is this normal ??

 

For a new vehicle? No obviously 30 seconds to shift is not normal.
for a 30yo vehicle with unknown miles? Not shocking.
Make sure the trans fluid is full