The introduction of leaver penalty creates a whole new issue when forming a party, as it's either the invitee getting a penalty if accepting the invitation and consequently leaving a match or the host that has to wait up to 10-15 minutes until the invitee(s) finish their game.
To kill this waiting time until the party is formed, I suggest having the current tutorial training mode removed after it has been completed (with an option in the menu to replay it for those 0.00..01% that didn't get it the first time) and replace it with a proper training mode that can be joined by all the members of your party. The map could be changed to something a bit smaller like a simulation dome from Titanfall 2, where your party would face waves of grunts, spectres, reapers, turrets, simulated bombardments or airstrikes, rooms filled with gas cans or barricated by electrified fences. A respawn beacon would be present in the center of the map, which would be the initial drop point for everyone, including friends that join the training mode later. Parts of the map could also be "outside the ring", with some high tier loot but also a serious sting (10-15 damage per second). The difficulty would increase with each wave, with the map resetting to initial state and difficulty after 10 waves or if all players die. Choice of legend could be available each time the training mode resets, but not allowing duplicate legends. Once the party is full, there could be a challenge mode switch becoming available somewhere in the initial drop area. Once a challenge mode is enabled, the team would have to do a specific set of tasks while facing tougher AI and a ring that is slowly shrinking. Scores would then be added to a leaderboard (teamname would be by default "<hostname>'s squad" - by the way, there should be a way to add a name to the squad if the host wishes to do so).
Alternatively, the map could have a triangular shape, with 3 respawn beacons in each corner and party members would play not only against AI, but also against each other (a mini-solo mode). Each corner of the map would have its respawn beacon protected by indestructible electrified fences and / or special gas traps that don't expire and can't be disabled, to prevent the player's "friends" from camping near his respawn location and troll him.
The training map could also feature some banners or special holographic devices that advertise the legendary skins from the shop, which could allow a player to equip that weapon or legend skin by a special interface and wear those skins until he is killed or the simulation dome resets and he gets respawned.
