By any chance does anyone know how long Shinji n Asuka have been together in universe?
There was the month Shinji stayed in LCL in canon, but before that it's probably just a month or two (if we assume an angel roughly every two weeks, and there Leliel, Bardiel and Zeruel between the kiss and the 'LCL' month), and maybe a week or two between the canon LCL month and Arael's attack. So at most they've been together three and a half months, at minimum a bit more than two months. Not that long, come to think of it.
Shinji was stuck in Unit-01 for 31 days, which overlapped Asuka's birthday.
As mentioned way back near the beginning of the thread, the timeline is nuts, with Asuka arriving in early September and all the Angels between Sandalphon and Tabris arriving between 24SEP15 and 31DEC15, a span of just 99 days, which has to include 31 days of Shinji's LCL-period. So that's 10 Angels in 99 days, only 68 of which are open. Additionally, 7 of them happen
before that 31 day break, meaning those 7 Angels all arrived between 24SEP15 and approximately 20NOV15, just 57 days. That's an Angel every 8 days, which is both crazy and incompatible with the spacing between them as stated in other places on-screen.
Sooooo, tl;dr, I felt little guilt in spacing things out. Shinji fights Sachiel earlier in spring, Asuka arrives earlier, etc. It was really needed to make things work, since I had Asuka say in the prologue that they'd 'been carrying on for the last two months'. That's two months since the Kiss, which took place just before Leliel. At this point our two lovers are still successfully concealing their relationship from everyone. It is in the aftermath of Leliel when Ritsuko orders Rei to spend all her time with Shinji and Asuka, starting that off. They visit Rei's apartment, and Asuka sees how the First Child is forced to live. Over the next two months, Rei figures out Shinji and Asuka are together, but says nothing, and is slowly weaned off the drugs she'd been taking, at Asuka's suggestion.
They've been together at least 3 months by the time Hikari is chosen as the Fourth Child, they go public at school, and Kaworu shows up. Asuka states later 'it's been 5 months since I left NERV-Berlin', but that includes a month at sea, and some weeks before she and Shinji got together after her arrival. By the time of her birthday party, Asuka tells Rei 'Six months ago I hated you'.
So by 'now', late December 2015, Shinji and Asuka have been a couple for about 5-6 months, concealing it from most people they know for at least half that time.
Ok, housekeeping note: The Christmas Special or Update, whichever I finish first, will go out on Page 1000. If I have to lock this to keep that, I will. In the meantime, let's hope this spurs me on.
For a hint on the Christmas Special, try to figure out what Kaji, Misato, Asuka, and Kyoko all have in common.