I reviewed the description from Merekov of the Red Army expansion 1939-40. Don't have translation of the sections for later 1940-41. Tho I have some analysis for that period from others.
Merekov describes a reasonably trained army of 1939, tho the effects of the ongoing purges were becoming apparent. The system for mobilizing reservists into new formations is described. In simple terms reservists sufficient for forming three new divisions were affiliated with existing standing units. To mobilize a new formation a portion of the standing or active units would be split off & create the cadre for the mobilized reservists. In October 1939 this process was started, but Markov describes a immense confusion created by frequent changes to this mobilization system, aggravated by many deep alterations in doctrine. These changes in doctrines at all levels are important in understanding why the Red Army performed so badly in 1941.
As it was the 65 infantry divisions of September 1939 would have created by mitosis 185 infantry divisions. Each requiring 6-9 months training to function at the level of a German formation of 1939.
Minimally trained takes 6 weeks. Less than that and you are a schelp with a gun
This is relevant at the squad level. It takes considerably longer to train platoon sgts & company grade officers. Between schools and field training you can get to some sort of minimum in a year. If your reservists have 3 years active service for sgts & junior officers you can get a company to a minimum capability in 1-2 months after mobilization. A bit longer for a rifle battalion. Once you reach regiment of any arm, it takes several years to train the command and staff & again several months to return these colonels and majors to speed when mobilized from reserve status.
The First problem for the Red Army at this point in 1939 is tho it had in theory cadre trained for a nominal 185 infantry divisions the reality was the purges were reducing that by close to 25% in 1939, & the purges were continuing. The Second bullet in the foot was the many changes in mobilization enacted 1939-41 was the expansion of the goal from 185 to 300+ infantry division, so 75% of the nominally trained cadre was being spread across 160 % greater infantry force. Even without the purges this was a showstopper. The third bullet were the numerous alterations in doctrine. These changes meant much of the training the reservist Captains, Majors, Colonels, and Generals was rendered meaningless. Rendered meaningless for the officers already on active service as well.
It took the US Army about 18 months to create what it considered a combat ready infantry division from zero. That included picking appropriate cadre from platoon sgt to general from a existing trained unit and sending him to a school specifically for his task in the new formation, then a incremental training system of 12 months. That was with a relatively stable doctrinal system, and a 'purge' confined to getting rid of elderly generals and political officers in the National Guard units. When the US Army started its mobilization in the autumn of 1940 it had between its Regular Army & National Guard NCOs & Officers and the Army Reserve Officers Corps cadre for approx 60 divisions. Over the next three years that was expanded to cadre and replacements for 90 divisions. By comparison the Red Army was asked to expand from a cadre for approx 250 Inf, Cav, & Mech divisions to over 500. & to do so in less than three years. Germany of 1934 had six years to expand to 150 divisions & seven to reach 180.