The custom is to eat an apple dipped in honey on the first night of Rosh Hashanah. The apple is not eaten before the meal, but rather after kiddush and after making hamotzi.
On the second night, one should have a new fruit and recite "shehechyanu." This is done before the meal, right after kiddush.
The Rebbe explains the difference between these two customs and their respective reasons.
Summary
When to eat the apple and the new fruit during the Rosh Hashanah meals, with their order and purpose in each night's observance.
Night 1 apple dipped in honey. Not before meal but after kiddush and the motzie.
Night 2 have a new fruit and say "shehechyanu". Before meal right after kiddush.
Explains the difference