There is no "good" time to have kids in this day and age, especially in law. You don't want to be pregnant during 1L, you don't want to be pregnant or have a child during 2L summer, you don't want to have a child while studying for the bar, you don't want to get pregnant during your first few years of practice, and by the time you're well-established as a senior associate you're well into your 30's and if you do have kids it will have to be on a very compressed time scale.
I don't think being pregnant during 2L summer is that bad, especially if you time it so your SA roughly coincides with your second trimester. When you start, you will not be very visibly pregnant, if at all. http://s72.photobucket.com/albums/i181/ ... eks001.jpg
. At that point, a loose blouse and jacket will hide the belly pretty easily. Even by the end of your second trimester you will not be one of those big as a house waddling pregnant women: http://i72.photobucket.com/albums/i181/ ... 4weeks.jpg
. It will be obvious you are pregnant, but not so obvious that people are nervous around you, as can happen when you're at the "about to pop" stage.
Strictly rationally, 2L summer is one of the better times to get pregnant, even as far as the firm is concerned. The firm doesn't have to pay for your maternity leave, they don't have an associate dealing with morning sickness, postpartum issues, etc. For you, if you deliver in September-November, you'll have almost a full year with the baby before going back to work, avoiding all the embarrassment and stress of having a newborn while working. If people at the firm object, it will be only for irrational reasons. I don't think it's fair to assume that people will react irrationally. I spent last summer at an NYC V10, and even in that high-pressure environment I can't see someone getting no-offered on the basis of being pregnant. Hiring decisions are generally made by a hiring committee, which almost certainly has women on it. They evaluate the feedback in your file. Even if they know you are pregnant, it's hard for that knowledge to make a difference in their decision based on how the process is structured. A single partner might, even unconsciously, choose a male summer over a pregnant female summer after a face-to-face interview, but that's much more difficult to do when you're deliberating with a group of people based on peoples' files.
There is, of course, some non-zero probability of getting no-offered because of your pregnancy. There is also a small but higher probability of birth defects if you wait till your 30's to have kids. There is a small probability you might never be able to have kids if you wait. Ultimately, you have to decide which risks you'd rather take. In doing so, don't over-exaggerate how likely firms are to no-offer you based on your being pregnant. A lot of male partners at my firm had young children. One senior associate I worked with took his kids to day care every morning on his way to work, and another up and took a month of paternity leave right in the middle of the summer and nobody thought anything of it. The fact of the matter is that you're not much more likely to get no-offered being pregnant as an SA, and at the same time nobody remembers SA's. If you're gunning for partner or something, people are much more likely to remember you taking a six-week maternity leave as a senior associate.