If the risk tolerance is tightened to 5%, the PNR is brought forward to 2022 for the 2K target and has been passed already for the 1.5K target. Including substantial negative emissions towards the end of the century delays the PNR from 2035 to 2042 for the 2K target and to 2026 for the 1.5K target.
Geoengineering can be done for a less than a few billion dollars per year. The cost has been estimated at about $5 to $8 billion per year. Not only is SRM relatively inexpensive, but we already have the technological pieces that assembled properly would inject the skies with particles that reflect sunlight back into space.