I don't fit the bottom plate until the end. I just slot the stub axle into the lower frame mounting, locate the top and start the lube bolt in the threads while it's all loose. Then add the bottom plate and use two threaded rods to compress the main spring, and ease the rebound spring into place.
The two fiddles are if the stub axle fouls the dust cover, or if the rebound spring goes a bit off centre. Either way, a bit of necessary force fixes it.
I used motorcycle spring compressors the first time I did this, but they are not necessary.
