Yes, the time differential is indeed an issue. However, I don't think that the Beleriand events need be as sketchy as you say. To use and add a bit to Marie's timeline for a second:
Kingdom of Doriath established.
Luthien born.
Dwarves enter Beleriand.
Thingol builds Menegroth. Daeron invents the Runes.
Orcs enter Beleriand.
Dwarves begin making weapons and armor for the Sindar.
Nandor enter Beleriand.
First Battle of Beleriand is fought
Denethor of the Green-elves slain and the Havens of the Falas are besieged.
Compare that to Noldor-focused elements
Flight of the Noldor.
First Kinslaying.
Doom of Mandos. Finarfin turns back.
Fëanor reaches Middle-earth and burns the ships.
Death of Fëanor.
Capture of Maedhros.
Maedhros sent to Thangorodrim
Granted, the events following the Noldor are described in more detail, but there is a lot of story in the Sindarin plotline! And it is certainly no more bare than the bones on which we hung Season 1.
Delaying the beginning of the plot is an interesting idea, but it is a bit problematic in terms of sketching out a plot arc for the season.
For a possible example, Act I would take us from the Oath up until the Kinslaying, Act II would be the Kinslaying through the Prophecy, Act III takes us from Finarfin's about face through to the Great Maritime Bonfire, and Act IV, from the Feanor's treachery to Fingolfin's arrival.