Is it too early to clear out mother's old belongings?

I agree with JKM. But watch what you get rid of personal wise. If not sure box it. Then someday when you have cleaned out, go back and see again if u want to clean out. Clothes, I only kept what I knew Mom would wear. She always wore slacks and tops. They only need a few pairs of comfortable shoes. Aides tend to put the same ones on every day. I got rid of all other stuff. I only took that seasons clothes into the NH and stored the rest at my house.

Jewelry in the home I would not do. It will go missing and aides may not have the time to make sure the resident has her jewelry on.

I agree - get busy cleaning out!

Go ahead and clean out. It's something you can do for her now, while she's unable to do it for herself. Since she's not likely to come home, you're doing the right thing.

Certainly, with a baby on the way, it's better to do this sooner rather than later. Babies have a way of sapping every bit of physical and emotional energy for a long time. You won't want to do it then.

Box it, bag it and call a local charity to come and take whatever you don't want or need. The Salvation Army, hospice-run thrift shops, and Habitat for Humanity have all been helpful to me. You make an appointment, and they arrive with a truck, put the stuff in the truck and hand you a receipt. Easy peasy.

No, it is not too early. She would not remember these things if she walked in the door in all likelihood, and the likelihood of her walking in the door again is very slim. Start now. You are nesting so it's a good time for it. Do it a bit at a time, a box at a time and you will understand that even YOU don't miss or notice that anything is gone. It's like I say of my "secret garden". I can trim and trim and trim and have containers FULL to the brim of cuttings and it looks like I didn't do a thing at the end of the day!

I would advise you to clear away, don't feel guilty. Just be careful not to discard anything that she might want or need currently. My mom is still living with me and I am slowly, conservatively, winnowing out the excess, the broken or worn out, the tacky. She's not aware enough to miss anything. Some of it breaks my heart, like her knitting supplies. She was a brilliant knitter but can no longer follow a pattern. But we have plenty of her hats and scarves and sweaters to treasure. I don't know if you have family members who might complain, none of mine would. I intend to ask family members to take anything they want after she's gone, so I don't want to discard anything valuable or sentimental, but I need to cut the clutter for us both.

Ok, now I'm confused. In your profile you say that your mom is only 43 years old yet she suffers from age related decline. I mean REALLY!!!
There is NO age related decline at 43 years old. And the fact that you're going to be having a baby next year certainly makes sense that your mom is that young.
So why is she really needing to be in a "nursing home" at her young age? We're missing a lot of pertinent information here I do believe, before anyone(myself included)can answer your question seriously.
So you may need to start over or at least tell us what really is going on.

Start with clearing out the easy stuff, not the personal stuff. I'm certain she also has old towels, sheets, etc that also need to go. She'll never miss them and you'll feel that you're making progress. Then work on the personal stuff. If you can identify a "special" bag or scarf or dress among the many then keep that one. Keep her jewelry as she can use a broach or bracelet in the nursing home. My dad wanted to keep a couple of suits that would never again fit him and he'd never have occasion to wear but he just wanted to know that he had them. Most of the rest of the stuff he never missed. Occasionally he'll ask me where a certain item is - never clothes but more keepsake items - and I just tell him that it's in a box in the closet even though it's long since gone to the donation bin. He's always been satisfied with that answer. Don't try to involve your mother in decision making as everything will end up being her favorite or something she just can't give up. This is a hard task for you but it's an important step to get into the next phase of both of your lives. If you do it thoughtfully and talk about getting ready for the new baby, not bringing up that she'll never be using these items again. And know that many of us have been in this situation and we know how hard it is.