I recommend getting a visual schedule for her day so you can add the quiet time on there. It will help her with school (now or future) and transitioning from activity to activity which will help her ability to regulate if she knows what to expect throughout the day. She’s going to be experiencing a lot of changes so a good routine can help especially once her sibling arrives. My little ones like the ability to pick in the morning or the evening before some of the activities of that day so helps create a sense of independence and autonomy
@Megan do you have a visual schedule you recommend? Or do you make your own?
A visual timer in their room can help. an Ooly or other stop light timer. Start with 15 minutes every day and increase it gradually. It took my child a year to not scream and cry about going to quiet time. It really helps get through the day now and plays quietly without any resistance. We also do a book and song at the beginning.
We use a smart light (Phillips Hue). We set a timer for an hour and fifteen minutes, and the light turns from a dim yellow to a bright blue when "reading time" is over. We have a Door Monkey because we sleep on a different level of the house so we need to keep him in his room away from stairs overnight, but we do close the door monkey for reading time. A potty break before hand is required. We do Reading Time right after lunch is done so there's no wondering on the routine.