We started ours really early. But that was largely because looking at baby things helped take my mind off of morning sickness and my husband was really eager to get it started. At that point we just added big gender neutral things that we intend to also use for future babies down the line. Now that we know we are having a boy we need to get back to it and add our gender specific items, we just have to find the time to do it.
I started really early because it gave me something to do while laying on the couch. I'm only registering on Amazon because my family is 17 hours away. I am going home for a shower but I want them to have the option to ship everything to my house. I am just making sure everything is free shipping. I'm going to find out what we are having but everything on my registry so far is gender neutral. The shower is only 4 weeks after I find out what I'm having and I don't want to throw it together and miss something or put something on that I don't need.
I personally wouldn't register until a month before your shower, if you register at Target. They will redo their complete layouts in their baby section, everything goes on clearance, and then no one can find the stuff you registered for. Spoken from experience...
I started my registry right after I found out what we're having. It's so much more time consuming than I had anticipated. I just work on it a little bit every night.
With my first (only time I registered) I registered for non-gender specific items early and did it online. Then everything else after the 20 weeks and actually went into the stores for that. They will give you a goody bag of samples when you go in.
I started mine this weekend we went (17 weeks) while we had time. Took 3 hours and still have to go online and re look at. Wanted to check out strollers and car seats and gliders before then and ended up getting both since mom is reimbursing for stroller/seat. All gender neutral really as we aren't finding out.
I did most of ours last week on amazon. Our family is all over the country so no baby shower and I figured it'd be easiest for people to shop online and have it shipped to us. We find out the sex in 10 days and then I'll add a couple last things and call it a day. My mom wanted me to do if early so that way she could start buying stuff a little at a time.
Re: register
Edit: I've picked non gender specific items such as the monitor, crib, mattress, stroller, and car seat.