1) Host a non-dedicated server, they will spawn in less than 10 seconds (normal hosting)
2) Tell hosters to restart their server more than once a day, once the server restarts all bots will spawns in 10 seconds, but if the hoster don't restart the server the bots will spawn very very very late, the longer it takes to restart the longer they will spawn. So if you restart now they will spawn in 10 seconds, 10 hours later they spawn in 1-3 minutes, 10 days later they will spawn in 15+ minutes.
3) The number of times you die affect bot's spawning speed, so if you whole team die more than 80 times in total it will takes longer for bots to spawn, stay ALIVE and
4) If there is 0 players on server it is better to make sure there are no bots on the first team, otherwise they will keep ended up killing themselves which will increase the amount of deaths on defenders which means it will affect the bot's spawning time alot
HOSTERS SHOULD REALLY RESTART THE SERVER 5 HOUR PER RESTART to COMPLETELY FIX THE BOTS SPAWNING LATE BUG, IF YOU CANT DO THAT PLZ HOST THE MOD FOR DEATH MATCH OR SOMETHING :D
If you host dedicated server the best way to fix bots spawning speed is to restart the server, its the quickest and easiest way, it only takes about 10-20 seconds to restart a server. Don't even bother hosting a dedicated server if you cannot host it every day/ restart twice a day