Some marketers are focused on making the sale right away. However, you may want to consider holding off until you are at least a few messages into your email sequence.
Now, this rule doesn't apply if people sign up to get a coupon or special product offer. Then they would expect that they are going to be sold to right away.
In fact, people sign up just to receive these special offers.
However if your list members signed up to get some valuable information, they may not take too kindly to getting pitched to right away. This is something you may want to test, but you need to think about the relationship first and the money later in most cases.