Effects are the result of the use of the power, so it doesn't not take place before the attack is made. That said, I don't have my books with me so...
My ranger player had 2 questions,
1- Sudden Surge has an effect line. When does that happen? He wanted to do it BEFORE the attack.
2- His beast has 2 healing surges. Does the beasts CON give more? I didn't think so.
There's been a lengthy discussion about this before. My conclusion:Also- If the Effect is before the Attack line, the effect is before the attack. if the Effect is -after- the Attack/Hit lines, it's after.