Some information on Army time in the Finnish Sport school.
There are two dates when a conscript can enter service in Sports School, either 17th of April or 3rd of July. For example, if a conscript is ordered to enter service on April 17th and doesn't show up, then the person is considered to be either a fugitive or AWOL. A conscript can ask for the order be delayed to next year, if he has a valid reason. For example, Lauri has asked for delay several years in row now, and it was always given.
The service time is either 165 days or 347 days (for those recieving NCO or reserve-officer training). Weekend- and other leaves granted (for example, performing exceptionally well in physical-tests (Cooper-test, swimming-test, etc) or shooting (gaining the golden marksman marker) are rewarded with extra leave; I would be so bold to claim Lauri is at least going to get the extra leave from the Cooper-test) to the conscript are included in the service time. I would bet Lauri intends to only serve 165 days
The first four weeks of Army time is the rookie period, the orientation phase. During that period conscripts learn the very basics of Army life; how to dress, how to salute, the military ranks, how to march, how to handle the personal weapon, and also the physical, mental and optical tests (only a small percentage of humans have the enhanced depth-vision required for Forward Observer duties). This is often the most stressful phase for conscripts as it is (especially for modern western people) so alien thing to live by a strict code; for professional athletes the time is pretty much normal life (except the uniforms and guns). Those serving in sports-school this is the period when there is the least possibilities to follow their personal training program (and I have understood professional athletes serving take these four weeks pretty much as a vacation), usually only about 2 hours per day.
After the four week orientation phase the branch of service training begins. For Sports school conscripts this means the personal sport training is upped to 8 hours per day (for example, the basketball athletes do all the normal basketball practices they would do anyway, in addition to 1-on-1, 3-on-3 and 5-on-5 scrimmages; this year there are in all 10 basketball players in Sports-school, which is way more than normal), and in addition the tactical training required in recon. Also all the evenings and weekends (minus a couple weekends spent in camping training in the woods) are free for the athlete to follow their personal programs or to rest (what ever they choose).
If the athlete is an international level athlete (like for example Lauri is), the conscript can be ordered to take part for up to 8 weeks in the sports training camp organised by the national Olympic committee (for individual sports athletes, like javelin throwers or ski-jumpers etc) or by the national team (for team sports athletes, like basketball players). In addition to that, an athlete can be ordered for up to 45 days to take part in sports events outside the borders of Finland (for example, if there would happen to World Cup in basketball in August-September, an international level basketball player like Lauri would be ordered to take part).
In short, Lauri probably is going to spend about 50 days of his 165 days service time at the garrison, because weekend- and other leaves plus the time commanded to spend with the national basketball team add up to about 110 days. Of those 50 days will be rather light physical service the first four weeks (for a professional athlete that is; for an average joe not that much into sports the first four weeks usually is the toughest time), and the remaining ~25 days (aka ~5 weeks) he will be spending following his personal training program (in addition to the scrimmages with the other basketball players doing their army time).
As far as I can see it, the main concern for Lauri isn't that he would come out of the summer out shape, but that he might be too keen to take part in all the possibilities. He has to remember to rest and take it easy at times too
