Sister Rant she's not ready for a child.

My sister just turned 23 last month. Shes married for almost 3 years now and has been a stay home wife for 2 year now. Shes my best friend and we are super close but if I can be honest shes a bit lazy and can be really immature at times shes the baby out of 5 of us and it definitely shows, shes never actually grown up. Her plan when she got married was to stay be a stay at home mom and planned on working up until she was pregnant but of course she quit her job as soon as she could once she was married beacsue she said she was stressed out she worked at a clothing store in the mall. I have to hear from her all the time how they dont have extra money cause she stopped working and just have enough for bills just and tiny extra for food. This of course frustrates me and I tell her all the time that she should try and find a job even if it's part time because it sounds like they could really use extra income. But instead she does nothing all day and I mean literally does NOTHING she stays up till 1-2am each night watching tv and playing on her phone she doesn't wake up till about 11AM sometimes later and that's because her husband wakes her up, and still barely manages to clean or cook her husband who works full time does all the cooking and most of the cleaning. Well yesterday she tells me that her and her husband haven't been careful for the last month and they're hoping to get pregnant by October so they can have a summer baby. Of course I feel excited and happy for them but I told her hey now that youre trying for a baby maybe you should start to get on a better sleeping schedule and help out around the house more because once the baby comes you're not going to have the luxury of just sleeping whenever you feel like it, a baby is hard work. She tells me "oh ya dont worry I got this I know what I'm getting into" but I honestly dont think she does. She's really not ready for a baby, she still acts and think likes shes 18 she knows nothing about what it's like to take care of another human being. I feel like I want to tell her that she should wait a little longer because I'm always upfront with her but feel like this may be something I shouldn't bring up.

**Edit to add- I probably should have mentioned this earlier but the reason I say I want to bring it up is because she does ask for my advice and input all the time. She calls me for every little thing to vent and cry, so yes I do feel like she would ask for tons of help and I fear she would get into depression like she did when she was working. I dont want her to live to my standards I just want her to really know what shes getting herself into. She has a lot of growing up to do