My husband & I are booked on BA flite leaving San Francisco & arriving in Heathrow at 11am T 5. We booked our daughter on a special student ticket(she's 22 years old ) with Virgin departing the exact same time & arriving in T 3. We then have a connecting flite to Paris on BA departing T 5 at 14:50. Now the problem, Virgin has changed the departure time from SF with scheduled arrival into Heathrow at 13:15. Heathrow's site advises a minimun of 90 minutes, which she'll just have, if they're no luggage and the same carrier. We can bring her suitcase and it appears that Virgin arrives earlier than it's scheduled to quite consistenly. I can move us all to the next flite to Paris which is 3 hrs later & arriving at 8pm. The thought of sitting in Heathrow for over 6 1/2 hours, during the middle of the night SF time(no we don't sleep well on planes) and missing the evening in Paris sounds quite miserable. Can she make the connection?
At the risk of sounding heartless- you will arrive comfortably on time and be able to make the connection (with your daughters luggage). Your daughter sounds old enough to look out for herself, and can probably run faster than you if her connection is tight. I assume you will know whether she makes your flight to Paris. Make a plan on what you will do if she misses your flight If necessary she could follow on the later flight? Last time we flew Virgin from Los Angeles to Heathrow they did arrive early
I wouldn't put too much faith in timetables, what time you arrive will largely depend on the strength of the gulf winds across the Atlantic.
More often than not atlantic flights are early going east. but if they're late they all tend to be quite a bit late, not just a few minutes. As suggested above, your daughter should be able to travel independently to Paris if things don't go according to plan.
Your daughter is 22 yr old, if she only has a backpack and doesn't have to worry about luggage then she can run to the gate. As others have said if she doesn't make it, they will put her on the next flight. Just make sure that she has the name and address of the hotel in Paris, at that age she can make her way to the hotel on her own. My daughter traveled all over Europe at the age of 20 and didn't have any problems so I'm sure your daughter will be just fine.
I fly both airlines into Heathrow every year, Virgin almost always is early or on time. If she hustles she will be fine, she can pick up luggage and make it just in time, primarily due to T-5 being very easy to navigate and check in along with security being fairly smooth. I would stay with the same plan. Good luck.