The most logical plan for me would be to do the following. Assuming they are going to lamb in April, I would give them their first jab sometime in early to mid January, then 4-6 weeks later around mid February give them their second jab. This will be 4-6 weeks before lambing so give the maximum transferred protection for the lambs. I would keep the number of injections to a minimum as it is not possible to use the same bottle for both injections and it is around £25 a time, which is expensive for only 3 ewes. Hopefully they might be tame enough then, to not be unduly stressed. Possibly try to find someone to share the doses with?