Structure data inside a Document database - json

Question

I'm building a app that is going to serve as an agenda or a scheduling book for some services. It's planned to the app to work in a "per customer" way, Angular in the front-end and to use the new Google Firestore, for all the real time and pseudo-backendless stuff.
The question is, as I have never worked with NoSQL databases before, how should I structure the data inside Firestore?
I thought about something that would look like this:
{
//Collection
"customer-a": {
//Document
"info": {
"name": "Customer A",
"Phones": [{
"contact-name": "",
"number": ""
}],
"address": {
"type": "street",
"name": "",
"number": 0,
"neighborhood": "",
"city": "",
"state": "",
"zipcode": "",
"country": "",
"coordinates": {
"latitude": "",
"longitude": ""
}
}
},
//Document
"config": {
"active-theme": "",
"themes": [{}]
},
//Document
"customer-data": {
//SubCollection
"employees": {
//Document
"employee-a": {
"name": "",
"phone": "",
"rattings": [],
"address": {
"type": "street",
"name": "",
"number": 0,
"neighborhood": "",
"city": "",
"state": "",
"zipcode": "",
"country": ""
},
//SubCollection
"schedulings": {
//Document
"2017": {
"total": 300,
"scheduling": [{
"client": {
"name": "",
"phone": "",
"rating": 5,
},
"price": 10,
"services": [{
"name": "",
"price": 10
}],
"datetime": "",
}]
},
"2018": {
"total": 300,
"scheduling": [{
"client": {
"name": "",
"phone": "",
"classificacao": 5,
},
"price": 10,
"services": [{
"name": "",
"price": 10
}],
"datetime": "",
}]
},
}
}
},
//SubCollection
"stock": {}
}
}
}
I'm thinking on splitting the scheduling into years because I think it may grow in size a lot, but as I said, I've never worked with this kind of database, so I don't really know how much data I could nest inside a document, for example...
As an exaggerated amount of data for a base calculation I thought about around 200k "objects" that would be stored for each employee per year, is that much or it's ok to store that much data nested?
Should I keep creating sub collections inside Firestore or it should be one single collections to store only different documents and nest everything?
Hope someone can help me,
Thanks.