Well, i've always preferred, with the Reformers, to let the text speak for itself, follow the clear meaning of the words, and where the text is not necessarily clear in one place (to the reader), to let other passages speak to the meaning of the 'unclear' passage.
In this particular case, the word translated as shortly is ejn tavcei...you can find and download the Greek font that i am using here in the event that you don't have it...
It is defined in Moulton's Analytical Greek Lexicon as:
tavco", ew", tov,...seiftness, speed, quickness, celerity; ejn tavcei, with speed, quickly, speedily; soon, shortly, Lu 18.8; Ac 25.4; hastily, immediately, Ac. 12.7 et. al.
"the time is at hand" in Rev 1:3 is the phrase oJ ga;r kairo;" ejgguv".
kairov" usually means "time" or "season" in the NT. It is the word ejgguv" that is of concern.
With respect to time, Moulton defines the word as
near, as to place, Lu 19.11 et al; close at hand, Ro 10.8; near, in respect of ready interposition, Phi 4.5; near, as to time, Mat 24.32,33, et al;
The most basic reading of the text indicates that the event(s) God speaks of is soon to happen. It is indicated by the context as well...why would God have John write immediately and send to seven churches if the events were distant future?