Keep the bark on...the moisture needs to leave the timber slowly and stripping the bark away just accelerates drying and promotes cracking. It might also pay to give the ends another coat of PVA...anything that regulates the drying will help. A 3" diameter log is going to take a couple of years to dry out, but you need to accept that a wood like laburnum is very prone to cracking, so a high percentage of waste could occur. If you get a major radial crack (from pith to bark) you can always ripm the branch along the crack. That give 1 1/2" thick pieces which are still usable for light-pulls, key rings and loads of other small projects.
Les