first setup and wifi with smartphone

Not really. You’d need a separate internet connection from your phone. Your phone can’t be a WiFi hotspot and control Sonos at the same time.

You could in theory use two phones, one providing a hotspot and another connected to that hotspot along with the Sonos devices, but in no way is that a supported arrangement. Moreover the first, hotspot, phone may refuse to support several WiFi devices at once. 

Thank you for this quick response. does this mean that if I have two phones I could configure the speaker and activate the Bluetooth while waiting to have my box? By using bluetooth I will no longer need to connect the speaker to my phone's wifi? THANKS

As far as I know this wouldn’t work, as Era speakers (like all Sonos fixed devices) require a network connection. 

Only the portable speakers (Roam, Move) are designed to operate in the absence of a network.

it would be absurd if that were the case.

It seems normal to me that a user can use a product offering Bluetooth or USB without an Internet connection. Especially for a living room speaker...

thank you anyway for your opinion

other opinions and answers are welcome

;)

https://support.sonos.com/en-gb/article/sonos-system-requirements

General requirements

• High speed wired internet connection such as cable, fiber, or DSL
• WiFi router

just because it’s noted doesn’t mean it’s not absurd. especially since from what I've read the requirement for an internet connection is for booting (which seems acceptable) but not for USB or Bluetooth use. this is not mentioned anywhere and again seems absurd

Sorry, but Sonos is a networked audio system. A network connection is definitely necessary for a unit to complete its boot process and accept commands from a controller. If a local Line-In or Bluetooth connection was configured to play it may continue to work for a limited time, perhaps until the IP lease attempted to renew, but there’s no guarantee either way.

What do you mean by “limited time”?

I am able to say with some certainty, that without a WiFi connection that only one (setup) Bluetooth speaker will play the audio (unless using Bluetooth dual TX) - you can’t get both speakers to play, as the stereo audio channel is routed to the other speaker in the pair over a wireless (not Bluetooth) network link. A BT dual TX will just simply stream the same audio to both.

Some mobile Hotspot devices and LTE (mobile sim) routers are not officially supported by Sonos (as already stated), but some may work - in some instances the mobile provider network may block some ports required for Sonos device setup - As an example, I’ve seen that reported recently with the UK 3 ‘Three’ network in a thread on this forum. Anyhow, if ports are blocked and the device will not setup/register, then you will find you cannot enable a Bluetooth connection on the Era 100s. 

In some cases though, these things may work and be setup ready for single Bluetooth use etc. but no guarantees. However you can always try these things and just see what happens.

Personally speaking, I would just get a much cheaper Bluetooth only speaker in the interim and then get the Era 100’s later after installing a wired internet connection to the Home and perhaps keep the BT speaker for use in situ next to the Barbecue in the garden (or some such similar activity).

Ratty: “until the IP lease attempted to renew”

In a bit more detail, Sonos speakers obtain IP (network) addresses from a DHCP server, usually on a router, and use this address to communicate across the network. The DHCP server sets a “lifetime” on each address and the speaker is required to check back to the DHCP server before that expires and obtain either permission to continue using the address or a new address.

I haven’t tried it but you might be able to use a travel router to provide the network that Sonos needs. The travel router would have to be connected to the Internet for setup, maybe with a second phone, but it could give you limited capabilities without the Internet connection for playing local music.