Egne, I try to avoid unclipping the quickdraws or untying the rope until threaded through the bolts. This means that if a bolt fails then I am still protected (though may have a few meter drop).
Once my sling is clipped, I will pinch the rope to thread through the bolts and tie a figure 8. I clip into the figure 8 and then untie my original knot and unclip the draws. It can sometime be difficult squeezing the doubled rope through the ring bolts but rarely impossible.