You can negotiate and offer "anytime" before you accept and start. As long as you have not accepted the offer letter, the whole 'negotiation' is still in play.You'll need to formally accept your offer. Initiate salary discussions. Let the employer bring up the subject. Salary negotiation doesn't have to be complicated! Before I accept your offer, I'd like to discuss the salary. I feel that the recent offer is lower than my expectations given the role scope. Do not accept an offer until it is in writing. It can also make it easier for you to draft up an official acceptance letter in response.