In general, most restaurants in Paris will accept childs/babies with no particular issues, except maybe in the expensive ones. A good way to check the restaurant acceptance is to ask for a 'siège enfant' (child seat), many restaurants have one or two ready for customers. If you intend to keep your baby in it's trolley, just be careful not to disturb other customers or waiters movements. You should look for a restaurant where tables are not too close to each other.
Most restaurants in Paris will not be open for service at 5 PM, they usually begin around 7 PM. This means you will need to look either for 'brasseries' type (the kind depicted by Gayot Fow), or all day service restaurants, which restrict your choice, especially if you're looking for typical french meal. You will find a lot of asian shops where you can get hot meals about any moment in day.Also in touristic areas, you have more chances to find an all day service place, but that might not be the best bargain ....
I will therefore suggest that you go for a nice walk around your hotel (depending on it's location) and keep your eyes open to find a place that suits your need. Having your baby with you can sometimes be an opportunity for social exchanges ('how lovely ! how old is he/she ?').
Extras : if you have a feeding bottle or some prepared food for the baby, most restaurants will happily warm it for you in their kitchen. Although public breast feeding is commonly accepted in France, it is more subtle to feel whether a given place is fitted for it.