@@GeorgeMunte How long is a piece of string? There is a reason 95% of dev projects go over-time and over-budget. At the first stage you have to perfectly outline exactly which features, systems, architecture, manpower (1 full stack dev? 1 frontend one backend dev? 1 designer, 1 dev.... etc, etc.).
Are you expecting the devs to do all the design? Do you also have a product manager?
The list goes on and on, and without extremely precise details upfront, I could give you a random number but it wouldn't be meaningful, or accurate.
Also, when it comes to financial products (like eToro) You're talking a completely other game. Not only are there SERIOUS security implications that need to be covered, but you can't just launch a trading app without implicit approval from the relevant agencies (depending on which country you live).