Talking to various people I've found the recommendation varies slightly from doctor to doctor, but typically it's two to three months.
Each time I've had mine done - initial lead implantation, second lead + two revisions - I've been advised three months restriction on movement. It's correct that you are not supposed to bend, twist or stretch. You are also not supposed to lift more than 2kg/5lb in weight. The reason for this is that the basic lead type - called a 'percutaneous lead' (or 'perc') relies almost entirely upon your body forming scar tissue for it to be anchored in place. It depends a bit on how targeted your area of stimulation is - sometimes just a few millimeters of movement can be enough to change a stimulation pattern (and therefore your quality of pain relief) entirely.
This can be overcome to some extent by using a 'plate', which is a different type of lead, however placing plates usually requires a partial laminectomy (i.e. removal of bone). So even though you've less movement restriction because of the risk of dislodging leads, you've a more invasive surgery and longer recovery time anyway.
In terms of pain after surgery, it's varied quite a bit for me. My first one barely hurt. My last one was excruciating. The doctor had to remove a lead and place a new one, and had trouble getting the new lead into place. In trying to get it in, he caused a fair bit of nerve root bruising and tearing of scar tissue which for a couple of months actually left me with more pain. Also be aware that the surgery is done while you're awake, and if you've been on opiates long term this can actually increase the pain of surgery.
I won't be around after mid-week, but until then if you've any other questions, please do ask.
CRPS since 1999, diagnosed in 2005 and since spread to full body, spasms, dystonia & contractures, gastroparesis, orthostatic hypotension,bradycardia/tachycardia, bone spurs, bursitis, carpal tunnel syndrome, osteoporosis, osteopenia.
On Oxycontin/Endone, Topamax, Mobic, Magnesium, Florinef, Midodrine, Somac, Cipramil. Have SCS, intrathecal pump with baclofen & bupivacaine and doing physio