@Neil D,
The problem with your theory is that its not at all theoretical. Remember a theory is a description of facts which have already been tested and demonstrated. Those facts must be axiomatic. In other words they must already have been demonstrated and are either self evident or have other self evident facts which demonstrate their validity.
So you can have a theory of say food preparation and its based on all the work done by bakers in the past. Things they already demonstrated as being factual (like for example if you bake bread for three weeks it will end up vaporised)
In the case of your specific theory it isn't a theory...its just an idea.
But without brushing it aside let me point out some things that have already been tested which you include in your idea. Some elements 'can' be tested. For one thing you mention the 'time' before the singularity. But since we know now that going backward time itself ceases to exist even 'before' we reach this singularity (since time is a product essentially of the interactions of subatomic particles with the higgs field) Then any description of time before this point is truly meaningless.
In other words no time whatsoever passed from the singularity state of the universe to the higgs field...there was no time. There might have been something in its place which had some of the properties we might describe as time, but it wouldn't be the same thing..., but there was certainly no time in the way we reference causes or effects.
Physicist explain most things as a spacial reference point anyway and often times 'time' is just one thing that gets in the way. For that reason time is dealt with in slices. But at the outset of the universe there was no time which under normal circumstances would make all descriptions easier, but of course without time no interactions are possible.
Einstein has little to do with this, in fact he was totally opposed to the idea of the expanding universe and had to be brought round to the idea by george lamaitre and edwin hubble.
I don't know of any other physicists that would think 'time' was present in this universe until there was something to allow it to be...for that you need matter, for matter you need mass, for mass you need something that makes mass.
This all revolves around the problem that time (and gravity) are in fact properties of other features of the universe...they are both a manifestations or side effects of something else, and indeed are changed by that something else. So time is altered by gravity, gravity by mass, mass by speed (or velocity) etc. Without any of these things there is no time.
However you could of course have sort of an eternity of time going forward...at least until all the matter in the universe dissolves first to subatomic particles, then to massless subatomic particles and finally they literally fall out of existence since they aren't in any way present... at that point time itself will cease to be. If you then wanted to ask how long that would remain the case the answer would be essentially 'eternity' since that's where time comes to its conclusion.
