My post was too short...
I-200 was the name of prototype and first "null" series of about 100 planes which on 9.12.1941 were called MiG-1. So when entered the phase of military tests in 41 IAP in late December 1940 they were already called Mig-1. The serial numbers of MiG-1 were 2001-2100. Serials of MiG-3 started from 2101.
By Chazanov, Medvied, Maslov "Istriebitiel MiG-3" Moscow 2003.
The name "LaGG" appeeared first in december 1940 - the name was LaGG-1 and was given on 9.12.1941 by the order of NKAP, when Factory No 23 was trying to produce first 5 aircrafts of this type. Name was later changed to LaGG-3 when production was started in Factory No. 21 - first plane accomplished on 10.02.1941. It looks like none of produced aircraft was called I-301 - prototypes only.
Jakubovich "Samoliety Lavochkina", Moscow 2002
In "Piervyi Yak" by Kuznecov there is information that 66 (for all 1940) I-26 of military trial and initial series were produced in 1940 (Factories No 115, 292, 303). So in this point info by Sobolev is corect. 5 I-26 were shown during 1st may parade in Moscow.The name was changed by the same decision of NKAP on 9.12.1940.
But we must remember that these planes were in tests - in NII VVS or-in case of Mig-1, in combat units under care of NII. So it may be possible than names I-xxx were not familiar to militay stuff of first line fighter units.
Now, I think we're clear
.